When Nick Clegg speaks by phone to David Cameron this evening, both men will be balancing their own immediate ambitions with the perceived medium-term interests of their parties.
Clegg may want to get Gordon Brown out of No 10 and be a kingmaker who props up the Tories, but his party may force him to deliver electoral reform. Conversely, Cameron may want to do a quick deal with the Lib Dems, but he is not in a strong enough position to defy his own party and offer real change on electoral reform.
Now Gordon Brown, Clegg and Cameron have to conduct the most important political discussions of their lives. These conversations will determine the future of their parties and future of the country.