PC/WI: KPD/SPD Popular Front in Wiemar Germany

An idea that's been rattling around my head for a while now is what would happen if the SPD and KPD were able to unite and both keep the Nazis out of power and become the ruling coalition in the Reichstag. However, it's still very sketchy at the moment and I was hoping to brainstorm the scenario a bit.

Plausibility

Firstly, when would be the most realistic time for both sides to start taking a Popular Front seriously, and what would have to happen to make it work? Even with a saner leadership the Comintern isn't going to abandon their Third Period position without good reason, so it stands to reason that the Nazis would have to be on the rise. Furthermore, even if the KPD were on board with the idea, would the SPD be open to the idea too? I'm thinking before 1925 would be too early, whilst after 1930 might be too late to make a difference, but I'm open to suggestions.

Secondly, who else would be in the Popular Front? The KPD and SPD alone probably wouldn't be enough to win. Presumably they would reach out to the other members of the Weimar coalition for support, but how willing would they be to work with the Communists?

Thirdly, how do we get the Popular Front to win? Even with a broad coalition they would still be up against a lot of opposition, and the entry of the KPD into a major coalition would likely drive moderates towards the right. Off the bat there are two things I think I could do. The first would be to pre-emptively wank the SPD and KPD so that they are able to bring in a good chunk of the working-class and unemployed voters who flocked to the Nazis IOTL. The second would be to split the right vote, possibly with a separate coalition of conservatives, centrists, and liberals who are opposed to working with the Communists but also distrust the Nazis. Whilst that wouldn't do much in legislative elections, because of PR, it might be a plausible way for the Popular Front to win the Presidency.

Finally, would it be plausible for the KPD to wrangle control of the Chancellorship as sort of a mirror of Hitler's rise to power?


Consequences

Firstly, how's this going to affect Germany. Would the military and/or the radical right attempt a coup? Is a German Civil War in the works? What sort of program would the Popular Front try to implement (presumably a very left-wing one)?

Secondly, what would the effect of a Popular Front Weimar be on international politics. At the very least it's going to mean Germany having much closer ties with the Soviet Union, which in turn is going to raise all kinds of hell. Poland are going to be terrified and France are going to be nervous, especially once the Spanish Civil War breaks out (which in turn is probably going to be different with Germany backing the Republicans).


Finally, what effect would closer and more open ties with Germany have on the Soviet Union on a political, economic, and cultural level?
 
I've always thought that KDP-SDP cooperation might actually lead to an *earlier* Nazi takeover by frightening the upper and middle classes with the specter of a "Marxist" government. In any event, such a coalition would not have a majority n the Reichstag. Even in the 1928 election, which showed a swing to the left, the KPD and SDP combined got only 207 seats out of 491 (42 percent), well short of a majority. https://en.wikipedia.org/wiki/German_federal_election,_1928 In 1930, they got 220 seats out of 577 (38 percent). https://en.wikipedia.org/wiki/German_federal_election,_1930 And very likely some people who voted for the SPD in OTL would not vote for it if they expected it to form a coalition with the KPD.

Nor is it easy to see such a coalition getting the support of other parties. The Zentrum had a right wing that was increasingly reluctant to cooperate even with the SPD--let alone the KPD!
 

Deleted member 94680

Nor is it easy to see such a coalition getting the support of other parties. The Zentrum had a right wing that was increasingly reluctant to cooperate even with the SPD--let alone the KPD!

Well, you could wank the Zentrum into splitting, maybe?

But, on the whole, I think the idea of a right-wing coup is the most realistic result of a SPD-KPD coalition in power. The only difference is that it might be the Army that launches the coup and a "General's Government" takes power - therefore blocking the Nazis' rise? Historically, the Heer sat by and, although uneasy with the prospect, allowed the Nazis to take power as they weren't the communists. If the KPD is in a controlling position and starts making policy and moving closer to the USSR, the Heer might well be 'forced' to act and stop democracy once and for all (it having proved itself to fail, as they'd see it). Whether they put serving Generals in positions of authority, or find ex-Generals and another form of the Cabinet of Barons is open to discussion.

After that, WWII would probably happen still as most of the 'politically minded' Generals were all anti-Versailles and were keen to regain Germany's 'lost territories'. It might just be that the course of action is 'more sensible' (no Anschluss, waiting for the military to be fully prepared and modernised, leaving competent Generals in charge, etc) with all that entails for the course of the War.
 
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