Warning! A bit long and I'll state up front my bias' are that I want a TL with the big 5-engine Atlas AND the Saturn-1
Ok, lets look at the big picture;
Assume for the moment that there is a higher level of support for ballistic missiles than air-breathing cruise missiles, (as a basis) starting around 1946. First of all at that time the ONLY viable way to deliver a nuclear weapon was in a manned bomber and there was a fight brewing over the one left over from circa-1942 planning: The B-36. Every service was seeing massive cut-backs and the Army was getting ready to go through birthing pains to separate the Air Force which, as the only nuclear delivery capable branch of the military was going to be taken a lot more seriously than either the Army by itself or the Navy. And on top of that you have Truman's "budget" process which pretty much was to take US income, subtract operating and reoccurring costs and whatever was left over was given to defense. Which is pretty much WHY there wasn't much money to be had for anything at the time. This didn't significantly change until Berlin and Korea pried money and support loose from Congress and the Administration but in a panicked way rather than a well thought out plan for realignment and refurbishment of US defense policy.
(Note: As bad as it is, "panic mode" seems to be the default thing with American politics and policy and it tends to shake loose a LOT of money and support. For a short time at least)
So we have a bit more funding for ballistic missiles but not much until about 1950, so between 1946 and 1950 we have the Air Force attempting to grab all nuclear delivery roles for itself and limit if not out-right try and get both the Army and Navy reduced or eliminated because they can't deliver nuclear warheads to the USSR anyway. So as background you have both the "Revolt of the Admirals," The B-36 Controversy, the controversy over the role and possible obsolescence of both the Army and Marines along with a huge amount of previous WWII projects and programs being canceled as money gets tight. Meanwhile massive drawdowns in forces in all three services AND the money issues means scrapping of a huge amount of materials and loss of man-power. Couple that with various and sundry political agenda's in the post war, but pre-Cold War years, "recession" and economic issues and you probably still see stagnation of overall research.
And by the end of this period NONE of the services are doing very well despite the supposed "dependence" on the newly minted US Air Force as the main branch of the military. (In 1948 less than half of SAC's bombers were considered operational and had little training or ability to carry out a successful bombing attack. That same year an exercise bombing practice on Dayton, Ohio fully half of the bombers MISSED the target by over a mile. And the only way to attack the Soviet Union would require a massive mobilization effort to move those bombers to Europe and Japan which was a dubious plan considering the state of the military transport and mobilization plans at the time.) It could be argued at this point that a political decision to depend more heavily on ballistic missile weapons rather than manned bombers would make a significant difference but it should be pointed out that this actually plays into the "unpreparedness" of US forces rather than address the problem as even with such a decision in hand they won't be really operational until the mid-50s. The main issue is without significant changes to the people involved, (Truman, Forrestal, Spaatz, Lemay, etc) most of the main factors driving how things played out OTL are still going to be there and aimed in the same direction.
By 1950 however you have the various shocks Berlin, Czechoslovakia, China, Korea, the Soviet A and then H Bomb, and so on and the realization of the threat and ramp up towards the Cold War required a serious re-thinking of policy and strategy. Not that the Truman administration hadn't used the two years since being re-elected to put their policies into overdrive and despite adjustments that allowed SAC to begin to ramp up and re-build capability, it was clear that support was for manned bombers and not missiles of any type. (Dewey may have been 'worse' in some aspects but really his election would have been a real "two-birds/one-stone" thing as it would have probably made an earlier reversal of the military decline, including reigning in the Air Force in part, but it would have also probably eliminated Eisenhower's Presidency which is both a good and bad thing. Eisenhower's "New Look" defense policy was seriously flawed from the start and while he DID do a great many good things he could have just as well seen many changes in an advisory role rather than setting actual policy. This of course will probably cause Nixon to have to wait until to get a shot at the big time and other knock on effects but that also may be to the good)
Meanwhile, depending on outside events you will have more progress on the larger 5-engine Atlas as no one knows at this point how big a "Super-Atomic" bomb is going to be. At the same time it would be likely that both the Army and Navy will have pursued larger and more capable missiles as well. Assuming, (since it's the basis of the thread

) that cruise missiles have less of a draw it's quite conceivable that the joint project that begat Jupiter would begin earlier as well. Again assuming less of a stigma over "rocket" research and a bit more support all around it is likely that more effective double-base solid propellant will be available prior to 1954 so both Polaris and Minuteman can come along earlier. However, the warhead size is a problem as while it was given in theory, (Edward Teller was telling anyone who would listen you could have bombs fitting in a brief case in a "few years" but it had yet to be actually proven) at this point no one is sure that the warheads can be downsized and it would be prudent to design to a larger sized warhead rather than a smaller. Guidance and CEP (Circular Error Probability) for ballistic missiles is poor, specifically for something like Polaris, so even if something like it is deployed earlier guidance and control is going to be similar to that used for Regulus or early Atlas and Titan missiles.
And it might very well be that the Army will be allowed to produce their own ICBM as many of the main supporters of ballistic missiles were less than enthusiastic about IRBM or MRBM missiles. (The Navy had a requirement due to shipboard or submariner deployment requirements. That Army not so much although they preferred the idea of mobile missiles to fixed installations) So instead of the Jupiter we know the Army could have fielded a different multistage missile. (While not really "German-worship" I have to admit that the Army in fact used the German knowledge base pretty well for their purposes but really Von Braun and company were really less interested in weapons than space launchers)
And while all this would have ended up giving the US the capability of launching an orbital satellite by the mid-to-late 50s it is still a question of if there would have been support for doing so prior to the Soviets or the IGY and if such an effort would be military or civilian in nature. We of course are aware of Ike's position on both but he wasn't alone and even though he was rather clueless and slow to understand the overall implications of Sputnik, there's some good points to be made about the effect or not effect as the case may be.
An interesting take is quoted here:
http://www.thespacereview.com/article/1059/1
"Ordway introduced Konrad Dannenberg, a deputy project manager on the Saturn V and one of the few remaining original members of von Braun’s “Rocket Team.”
Dannenberg stated that when Sputnik 1 was placed into orbit, the incoming Secretary of Defense, Neil McElroy, just happened to be touring the Redstone Arsenal and meeting with the commander of the Army Ballistic Missile Agency General Bruce Medaris, Wernher von Braun, and several others. Von Braun immediately recognized his opportunity and informed McElroy that his team could place an American satellite in orbit in sixty days. Medaris intervened and suggested that ninety days was a more realistic target. McElroy gave them the approval and they ultimately managed to achieve the goal with Explorer 1 just ahead of their deadline.
In fact, von Braun had been secretly working to develop his own satellite and space rocket after losing the competition to build the American “scientific satellite” in 1955. He could offer an optimistic estimate because—violating Department of Defense orders and probably misappropriating government funds—he had already built some of the necessary hardware and had a rocket in storage. In 1956 and 1957 he had lobbied the Department of Defense to reverse the decision, to no avail. Now he finally had his chance.
Dannenberg also said that in retrospect, it was good that von Braun and the Army team had lost the 1955 selection. Had he succeeded, the United States probably would have launched the first satellite into space—to little fanfare. Without the controversy surrounding the United States being “beaten” by the national of peasants and tractor builders, it is unlikely that as much money would have ultimately flowed into the American space program. There may have been no NASA, and no Apollo lunar program, Dannenberg speculated."
My own take is that this may be somewhat correct in that had the US gone first it would have been pretty "ho-hum" as the public had been previously introduced to the general concept of spaceflight by the Collier's and Disney space flight entertainment series'. But the money WAS in fact flowing and having the Soviet's go "first" would have ensured it not only continued but probably increased. Where I differ is the idea that "NASA" and "beating the Russians" while substantially different would not have still happened. There was already Congressional as well as Administration efforts and pressure to reign in the multiple and often repetitive efforts aimed at US space flight. More so as there was no single focus or coordination in the efforts. Granted a large majority of this was the intensified inter-service rivalry engendered by the post-war years austerity and forced competition due to policy. politics and that same inherent historic rivalry, but there was a huge amount of wasted and duplicated effort just the same. While it is arguably possible that without the Sputnik Panic (and the follow up Soviet first manned orbital flight) that the US would not have pushed for the Lunar program as we did I very much doubt that there would have been no incentive for manned space flight and an eventual mission to the Moon. (And beyond)
As it was the Sputnik Panic brought us not only NASA but also ARPA which initially was in charge of organizing and directing the US space efforts before everything was folded into NASA. Frankly I see ARPA as being somewhat inevitable really as it was something that was needed to coordinate high-end military research and development which until that point was haphazard at best. NASA on the other hand was specifically established to become the civilian "face" of the American space effort and while it was initially suggested that it would coordinate and oversee America's space program in reality it was aimed specifically at ensuring American MANNED space flight would be as free from military influence and control as possible. There were obviously OTHER American space programs that continued on outside of NASA such as NRO and military specific programs, but the end result was that any military "manned" programs were quickly rendered superfluous and dropped. I don't see this as inevitable either though.
Thoughts?
Randy