Ryan accepted his nomination as Romney’s running mate at the Republican convention, drawing repeated roars from delegates with promises to challenge President Barack Obama’s economic policies.

A fiscal conservative and budget expert, Ryan said the White House race would offer ‘the clearest possible choice’ at the Nov. 6 election about possible economic remedies.

‘Before the math and the momentum overwhelm us all, we are going to solve this nation’s economic problems,’ Ryan said on Wednesday in a speech that served as the little-known Wisconsin congressman’s introduction to voters.

‘We will not duck the tough issues - we will lead. We will not spend four years blaming others - we will take responsibility,’ he said. ‘So here’s the question: Without a change in leadership, why would the next four years be any different from the last four years?’

Romney’s selection of Ryan, chairman of the House of Representatives Budget Committee, has energized party conservatives who have doubted Romney at times and has put Ryan’s proposed changes to Medicare, the popular health program for seniors, at the centre of the campaign debate.

Ryan’s budget plan would rein in government spending and shift some Medicare participants into private insurance plans purchased with the help of government subsidies, a proposal that Democrats charge would put future benefits for seniors at risk.

Republicans hope to strike a balance at the convention between sharp indictments of Obama’s leadership and a broader introduction of Romney’s plans for the economy and the softer side of a candidate who has had trouble connecting with voters.

The convention seems to be boosting Romney so far. A Reuters/Ipsos online poll on Wednesday showed Romney deadlocked with Obama among likely voters at 43 percent each - an improvement for Romney from Obama’s two-point lead on Tuesday and four-point lead on Monday.