Vice President Joe Biden will step on the stage at Centre College in Danville, Kentucky for tonight’s vice presidential debate in the role of the relief pitcher for the starter who seemingly got knocked off his game. After the somewhat lackluster performance of President Obama in his first match-up against Mitt Romney, allowing his Republican challenger to get a second-wind, Biden is now being asked to regain the incumbent’s advantage. With polls showing a slight surge by the Romney ticket, tonight’s debate is important to both campaigns. Despite his reputation for going off-script, Biden, a veteran of the Hill, is more than capable of delivering for the Democratic ticket. What is more of a question mark than Biden is Republican vice presidential candidate Paul Ryan’s command of the stage in a live debate setting.

Tonight’s debate will cover foreign and domestic topics, divided into nine timed segments of approximately 10 minutes each. The moderator is ABC News senior foreign affairs correspondent Martha Raddatz and she will have her hands full. The performance of PBS’ Jim Lehrer as moderator of the first presidential debate has been widely criticized so all eyes will be on Raddatz to see if she will have a firmer control of the debate.

Paul Ryan is expected to be the message carrier for the Romney ticket and will likely follow the script of bashing the President over the pace of the economic recovery, and seeking to exploit the tragic events at the U.S. embassy in Libya that claimed the lives of Ambassador Chris Stevens and three American staff. Ryan will serve as an interesting debate opponent given his very public role in fashioning the GOP budget response and his Medicare proposal. He will likely take a much more aggressive posture than his running mate, as this is the only debate between the vice presidential candidates. Given his experience and familiarity with Congress, Vice President Biden will be well positioned to challenge Ryan’s budget assertions and years of service on the Senate Foreign Relations Committee, including as chairman of the panel, should give Biden a significant advantage during the segments devoted to foreign policy. The Vice President’s Achilles heel is his tendency to run off the rails and make unscripted comments that are well intentioned but get mangled in translation. In debate preparation the Obama campaign likely put forth scenarios to Biden that could invite trouble or misinterpretation in his response. At this point the last thing the Obama camp needs is an errant comment that the Romney campaign or third-party could embed in an ad.

For Paul Ryan, tonight is his real national debut. His speech at the Republican National Convention pales in importance to how he performs at this debate. While the vice presidency receives short shrift in the eyes of the electorate, history suggests that attention should be paid to the person who could infamously be one heartbeat away from the Oval Office. In the last fifty years we have witnessed two occasions when the Vice President was elevated to the presidency, and in both instances the nation was well served by two veterans of Capitol Hill. Ryan has been the GOP’s pit bull but now he faces the tall task of convincing the electorate that he is presidential material. Though he must tow the Romney campaign line, Ryan has made enough waves himself in Congress to also have to defend his own policy positions. How he does that and if he can do so without sounding smug will greatly influence post-debate perceptions about his performance.

Vice President Biden is not without his own hurdles to clear. The most obvious is maintaining his train of thought and not freestyling at the microphone. Despite his many years in Washington, Biden often implodes when he tries too hard to connect to the public. He often takes that one extra step that often lands him in a communications ditch. For the Vice President to be successful tonight, he must resist the ad libs but use his tremendous experiential advantage to demonstrate his ticket’s far superior governing capabilities. Biden’s compelling personal narrative should also be interjected to give voters a sense of his commitment and passion to public service. In many ways, if he can remain focused and on message, Vice President Biden is the campaign’s secret weapon. He is to Obama what Dick Cheney was to George W. Bush, the elder statesman who should bring comfort to partisans and independent voters who believe experience and knowing the ways of Washington is important to governing. Biden can’t come off as lecturing Ryan but if he can paint the Wisconsin legislator as a naïve novice it will have the same effect.

Tonight’s debate is the undercard of next week’s main event at Hofstra University when President Obama and Mitt Romney will square off for their second debate. A draw does not help the President’s electoral fortunes. Vice President Biden must at least deliver a technical knockout to shift the momentum in the closing weeks of the campaign.