[Greece] Let's say SYRIZA somehow managed to get the highest number of votes and thus the 50 bonus seats in June 2012, and let's say the KKE still barely survived the threshold. What would happen next? Could Tsipras really have formed a government? Is it possible for another election to take place a month later?
If he somehow manages to form the government, what would be the reaction of other European states? Could Greece really tear off the EU/IMF memorandum, without leaving the Eurozone giving that it is impossible to expel Greece from the Eurozone immediately?
Yes, he would have formed a government with the Independent Greeks and DIMAR (if SYRIZA and the Independent Greeks didn't have enough MPs). He would tour Europe trying to convince Merkel that the memorandum will harm Greece and Europe in the long run, but he probably wouldn't have been very successful at least with the Northern Europeans. Much would depend on how France and Hollande would react. If Hollande endorses the SYRIZA positions, the memorandum would be modified to avoid some job cuts and some of the other harsh measures.
Edit: Here's a scenario I came up with. 92,563 OTL KKE voters vote for SYRIZA instead. 77,913 OTL New Democracy voters vote for a smaller party that fails to reach the 3% threshold. KKE is exactly at 3% while SYRIZA barely wins the election.
The parties by number of MPs:
SYRIZA 127
New Democracy 76
PASOK 33
Independent Greeks 20
Golden Dawn 19
DIMAR 17
KKE 8
After the May election, SYRIZA had the support of DIMAR and the Independent Greeks in order to form a government. PASOK would have probably also supported a SYRIZA government to avoid deadlock, but they needed a 5th party. Tsipras approached KKE, but the communists refused to work with him.
If the results were as above in the June elections, a SYRIZA-Independent Greeks-DIMAR coalition would have 166 MPs and would be able to form a government.
DIMAR would probably not participate in the government (I am making that assumption because they're not participating in the current government) while the Independent Greeks would have probably asked to be in control of a few cabinet departments such as the Department of Defense.
As I said above SYRIZA wouldn't be able to tear off the memorandum, but if Hollande provided support, they would have probably been able to re-write it.