How is Kerensky going to do this? The Kadets and moderate socialists would violently oppose it. [1] Kornilov and the other future White generals would oppose it. (To quote an old post of mine: "Kornilov was definitely for continuing the War. 'The Provisional Government, under the pressure of the Bolshevik majority in the Soviets, acts in full agreement with the plans of the German General Staff . . . I cannot betray Russia into the hands of its historic enemy, the German tribe, and make the Russian people slaves of the Germans.'"
https://books.google.com/books?id=kdQFBAAAQBAJ&pg=PA107)
And the Bolsheviks would be the first to cry "treason" and "sell-out to German imperialism." Of course, they were in favor of peace, they would explain--but with the German "workers and soliders," not Wilhelm II. If reminded that the German workers and soliders were not in power, the Bolhseviks would reply that if only Russia got rid of the PG and established a genuine Socialist government, a German revolution would be sure to follow...
Kerensky wouldn't last a day if he tried to pull off a Brest-Litovsk.
[1] To see the political impossibility of Kerensky making peace, one just has to look at the moderate socialist parties on which he depended for his support. I'll recycle something I wrote some time ago about the extraordinary tenacity of Russia'a moderate socialists on the war:
In December 1917 the Party of Socialist Revolutionaries held its Fourth Congress. The extreme left of the party had already defected to form the Left SR Party but there were still people of quite left-wing views at the Congress. One of them, Kogan-Bernstein, proposed that the forthcoming Constituent Assembly summon the Allies to begin peace talks without delay, and in the event of their refusal or failure to reply within a specified time limit, Russia would have a free hand. The resolution did not say how this freedom would be used, but it did at least imply separate action if not a separate peace. The resolution was voted down 72-52 with 32 abstentions. (Oliver Radkey, *The Sickle under the Hammer: the Russian Socialist Revolutionaries in the Early Months of Soviet Rule*, p. 192.) And this was after not only the disastrous summer offensive but the October insurrection! Yet *even then*, only one-third of the mainstream SRs were willing to demand tangible progress toward peace, even at the cost of breaking with the Allies. So how likely were they (or their similarly-minded Menshevik comrades) to do so several months earlier?
If there was anyone who just might have filled this role, it could have been Victor Chernov, leader of the left-center of the SRs, a man who had resigned from the PG protesting its dilatoriness on the issues of peace and land reform, and a man who was very popular in the Russian village. If only Chernov's faction of the SRs had either gained control of the party or formed their own party; if the Constituent Assembly elections had been held months earlier; if Chernov's backers had won; and if the Assembly had made Chernov Prime Minister of Russia, the country would at least have had a leader of greater legitimacy than Kerensky and perhaps more willing to confront the Allies. Chernov later claimed that while he had opposed a separate peace in 1917 he would have been willing to consider one as a last resort if the struggle for a general settlement had meant the immolation of Russia on the altar of the Allied cause. Unfortunately, Chernov's actual conduct during 1917--including during the Fourth Congress--was marked by constant compromising with the pro-war right-center of his party, and as Radkey remarks "if he could not see signs of immolation in the situation of December, 1917, then he would never see them." (p. 190)