US vice-presidential candidates Joe Biden and Paul Ryan are preparing for their televised debate on Thursday in the knowledge that a strong performance during last week’s head-to-head from Mitt Romney has closed the gap with President Barack Obama to just two points.

Polls over the weekend suggest that the White House incumbent has maintained an advantage in the race, but one that has been severely eaten into following a lacklustre performance at the inaugural debate. An Ipsos/Reuters snapshot of voter intention put Obama ahead on 47 per cent to Romney’s 45 per cent.

Already, the Ryan camp has sought to manage predictions. Ryan told reporters last week he expected Biden to come at him like a “cannonball”, while Reince Priebus, chairman of the Republican National Committee, said that he expected the Wisconsin congressman to do well, but noted that Biden is a talented debater.

“Paul is a smart guy. He has committed his life to understanding the problems of our economy,” Priebus said on CNN’s State of the Union. He said he thought Ryan would do a great job, but Biden was a gifted orator and “very good at rhetoric”.

The two men will face off for the first time on the public stage in Danville, Kentucky, and the stakes are high. Biden, 69, who has served in the Senate for 36 years and run for president twice, is under pressure to make up some of the ground Obama lost on Wednesday.

There was surprise that Obama did not employ attacks he has previously used to good effect. There was no mention of Romney’s ill-advised quip in which he dismissed 47 per cent of Americans as welfare-takers who believed they are victims, nor of his record at Bain Capital.

Biden is expected to go after his opponent’s key arguments on taxes, entitlement reform and deficit reduction.

Ryan also has a tough job ahead of him. At 42, he has 14 years in Congress to Biden’s almost four decades and has never debated at a national level. He stands to prove himself as Romney’s running mate, while defending his position on taxes.

Analysts predict that both men will stick to the issues they have discussed on the campaign trail, while fleshing out some of the differences between them.

However, they have an additional dimension to consider — not eclipsing the boss. Alan Schroeder, a Northeastern University journalism professor, said in the Courier-Journal in Kentucky: “The vice-presidential candidates have to be a little careful about not getting in front of the news and not getting in front of their top-of-the-ticket partners.”

Biden, who has a reputation for gaffes, told reporters last week that he had been studying Ryan’s position on the key issues carefully. “I just want to make sure that when I say these things, I don’t have the congressman saying, ‘No no no, I don’t have that position’,” Biden said.

Ryan got his criticism in early, saying: “He’ll be in full attack mode, and I don’t think he’ll let any inconvenient facts get in his way.” — The Guardian, London