[cnn-photo-caption image= http://i2.cdn.turner.com/cnn/2008/POLITICS/08/26/dnc.wednesday/art.bill.clinton.gi.jpg caption="Close attention will be paid to what former President Clinton says about Barack Obama."]
(CNN) - Sen. Joe Biden will make his first appearance before the Democratic National Convention as his party's vice presidential nominee Wednesday night, but the real drama of the evening may come from former President Clinton and what he says about Sen. Barack Obama.
"I think things are actually progressing better than maybe some of us might have thought in terms of the relationship between the two of them," said Paul Begala, a Democratic strategist and CNN contributor.
"They haven't known each other very well or very long. And Sen. Obama ran against his wife, and there's still some bruised feelings, but I think the president and Sen. Obama are trying very hard to reach across that divide."
As the Democrats gather for their third day in Denver, the theme of the night will be national security, an issue traditionally owned by the Republicans. Some of the Democrats' most experienced statesmen are expected to argue that Obama is the best candidate to strengthen America's national security.