( CNN ) -- What a difference two debates have made . Before the first presidential debate last week , President Barack Obama appeared to be cruising toward re-election and possibly a thumping victory . After the first presidential debate , that changed dramatically : Suddenly , we had a horse race . Now after the vice presidential debate Thursday night , we not only have a horse race , but partisans fired up on both sides . Joe Biden relit the fire under Democrats in a passionate , often dominant tangle with Paul Ryan . Going into that encounter , Democratic spirits were not only drooping but some were beginning to panic that they were throwing away the election . Biden put a forceful stop to the caterwauling -- or , as Gloria Borger put it , righted the ship . He was especially effective in countering Ryan on Medicare and ( as Van Jones argued after the debate ) in making a case that a Romney administration could mean the end of Roe v. Wade . An old pro , Biden knows how to play to seniors , women and the middle class . Opinion : Debate coach -- it 's the Biden show ! But Republicans took equal encouragement from Ryan 's performance . And well they should . Ryan was a steady , unflappable presence onstage who made an articulate set of arguments in favor of conservative principles while also seeming sensitive and reasonable to many moderates . Ryan was also surprisingly strong on foreign policy , holding his own against a man far more schooled in the subject . Overall , he more than justified Mitt Romney 's judgment in choosing him as running mate . On substance , I called it a draw right after the debate ( as did Wolf Blitzer and a few others on our CNN team ) . That was good news for both Biden and Ryan . The latter could claim credit for being one of the only two challengers who has ever fought a sitting vice president to at least a draw , the first being Al Gore against incumbent Dan Quayle in 1992 . The CNN poll of registered voters who had watched the debate reached a similar conclusion : Forty-eight percent said Ryan won , 44 % said Biden , though the difference was within the poll 's margin of error . A CNN focus group thought it was a draw as well . ( Note to candidates : What the focus group liked most was when Biden and Ryan said what their administrations would do to fix the economy . Could we possibly hear more of that in the remaining presidential debates ? ) But there was another element to the debate that has aroused more controversy . As it did in the first presidential debate , CNN chose to show the two candidates on a split screen throughout the evening . ( Good call ) . Watching that , I found Biden 's frequent laughs at Ryan to be off-putting -- and indeed , condescending . That plus the interruptions were in stark contrast to Ryan 's calm , even-keeled performance . So on style , I thought the edge went to Ryan . Opinion : Feisty Biden , wonky Ryan . As often happens in these highly charged times , many Democrats sharply disagreed with that judgment on Twitter . They thought I along with some colleagues were jackasses ( that is a very polite rephrasing of their language ) . Many cited a CBS poll after the election that found Biden a clear overall winner . What was lost in translation is that the CBS poll was of uncommitted voters and the CNN poll of all registered voters . Recognizing there can be honest differences , I stand by my call -- Biden was overbearing in the early part of the debate and that diminished the impact of his arguments . Taken altogether , the vice presidential debate did make a difference : Biden was able to help his boss out of the hole -- he helped to stabilize the race . But Ryan was able to keep the GOP fired up , too . Both campaigns now gallop forward , looking toward the next showdown this coming Tuesday night when CNN 's Candy Crowley is the moderator . It 's a close horse race with passions high , fans on their feet . The opinions expressed in this commentary are solely those of David Gergen .
David Gergen : Two debates in two weeks have transformed presidential race . Gergen says the polls have tightened , partisans on both sides are fired up . CNN poll gave a slight edge to Paul Ryan ; Gergen says he had edge on style . Gergen : Tuesday 's town hall debate looks increasingly important .