DAnville, Kentucky: Joe Biden enters the sole US vice presidential debate with Paul Ryan Thursday needing to reverse the Republican tide unleashed by his boss Barack Obama's own poll-sapping performance.
Vice President Biden, 69, will go head-to-head with Ryan, 42, in Kentucky, eight days after Republican nominee Mitt Romney transformed the race to the November 6 election with a barnstorming take-down of Obama in the first of three presidential debates.
Biden, a beaming, back-slapping veteran, has been in Washington since Ryan, the Republican rising star and fitness fanatic who has emerged as the ideological north star of congressional conservatism, was a toddler.
An accomplished debater known for delivering killer put-downs with a dash of Irish-American blarney, Biden is likely to land blows that Obama kept sheathed during his clash in Denver with Romney: a showing that mystified the president's supporters.
Biden offered a hint of his strategy as he boarded his plane headed for Kentucky: "you ever see me rope-a-dope?" he asked a reporter, referring to Muhammad Ali's famed on-the-ropes tactic designed to exhaust an opponent.
En route to a couple of campaign events in key swing state Florida, Obama called Biden from Air Force One to wish him luck ahead of the high-stakes encounter, spokeswoman Jen Psaki said.
Obama campaign manager Jim Messina also hinted that Biden would come out swinging in the debate, to be moderated by ABC News correspondent Martha Raddatz and beginning at 9.00 pm EST (0100 GMT Friday).
"Joe Biden, as he always does, will speak the truth," he said, hinting that the vice president will zero in on what Democrats see as serial untruths cast by Romney in last week's debate on issues like taxes and health care.
"There is no hiding when you are president. People need to know where you stand, and what you believe in."
Diane Black, a Republican lawmaker who has spent long hours with Ryan crunching budget numbers, predicted the vice presidential nominee would "shine" despite his perceived disadvantage on foreign policy.
"Paul is really a smart man and he is going to be on his game with all of the issues tonight," Black told CNN.
Obama, who will watch Biden's debate aboard Air Force One on his way home from Florida, told ABC News that his number two would do fine, framing it as: "Joe just needs to be Joe."
But that scenario worries some Democrats, aware of the voluble Biden's penchant for gaffes -- including a remark earlier this month that the middle class had been "buried" during Obama's presidential term.
Biden however was under similar pressure four years ago and successfully navigated the treacherous gender politics of a debate with then Republican vice presidential nominee Sarah Palin.
Generally, vice presidential debates, the undercard to a trio of clashes between the presidential nominees, are not seen as pivotal moments in White House campaigns.
But Obama's debate showing in Denver last week was so limp that Democrats badly need an injection of morale and enthusiasm after a week in which Romney rehabilitated his image and drew level, or into the lead, in some polls.
Rasmussen Reports had Obama up a single point in its national poll of likely voters Thursday, while Gallup had a similar margin but with Romney on top.
A flurry of state polls Thursday revealed the race was essentially becoming a toss-up.
An NBC/Wall Street Journal survey had Obama up six points in what may be the kingmaker state, Ohio, but two other surveys in the state said the race was within a single point.
Romney had narrow leads in other battlegrounds Colorado and Virginia, while Obama was up in another Virginia poll and led by one percent in Florida, while there were signs of a narrowing race in other key states.
Despite the tightening polls, Messina said that the Obama campaign believed all of its multiple routes through battleground states to the 270 electoral votes needed to win the White House remained viable.
As well as hammering Romney, Biden is expected to challenge Ryan over a budget he authored for House of Representatives Republicans that included cuts to spending on Medicare, the state-financed health scheme for elderly people and other popular social programs.
But Ryan has a facility for explaining complicated fiscal policy, so supporters are confident he will at least carry the Republican ticket to a draw in the debate.
Neither protagonist will ride into the debate with plump approval numbers, perhaps due to Biden's role as the Democratic ticket's attack dog, and Ryan's identification with unpopular House Republicans.
Biden had a 44 percent favorable rating in a recent Gallup poll, a point ahead of Ryan.
Thursday's clash will serve as a warm-up act for the final two bouts between Obama and Romney, in New York state on October 16 and in Florida on October 22.