Mitt Romney, the US Republican presidential candidate, has chosen Paul Ryan, Wisconsin congressman, as his vice-presidential running mate.

Romney appeared together with Ryan, who chairs the US House of Representatives Budget Committee, at an event in Norfolk, Virginia on Saturday to announce his pick for vice-president.

Romney said Ryan, 42, "has become an intellectual leader of the Republican Party", and stressed that their campaign will focus on ways to create jobs, protect Medicare and Social Security, and repeal the health care law enacted under Democratic President Barack Obama.

"His leadership begins with character and values ... Paul Ryan works in Washington but his roots remain in Janesville, Wisconsin," Romney said.

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Al Jazeera's Alan Fisher, reporting from Washington, said the choice of Ryan is, "a statement by Mitt Romney that he believes that the economy is the most important issue".

He said despite Ryan's age, after 13 years in the House he was experienced.

"[Romney] has said persistently over the last few months that whoever he picks as vice-president should be able to lead in their own right if anything ever happened to him," our correspondent said.

When the time arrived for Romney's big introduction of Ryan on stage on Saturday, Romney's tongue briefly let him down.

"Join me in welcoming the next president of the United States, Paul Ryan," a beaming Romney said at the event in front of a retired battleship USS Wisconsin.

Moments later Romney returned to the podium. "Every now and then I'm known to make a mistake. I did not make a mistake with this guy," he said of Ryan.

But he corrected himself, saying the Wisconsin congressman is "going to be the next vice-president of the United States".

Bold choice

The announcement marked the end a months-long search by Romney for a running mate to join him in facing Obama and Vice-President Joe Biden in the November 6 election.

His choice of running mate is a bold one and comes after polls this week showed him falling slightly behind Obama in what is still a close race, in a campaign that is focused largely on the weak US economy.

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The selection of Ryan brings a measure of youthful exuberance and energy to the Republican ticket as party activists prepare to gather in Tampa, Florida, late this month for a convention to formally choose Romney as their presidential nominee.

Ryan's selection also immediately draws attention to a budget plan he proposed as House budget chairman that would include controversial cuts in government health programmes for the elderly and poor.

"We're in a different and dangerous moment. We're running out of time and we can't afford four more years of this," Ryan told the crowd.

"Politicians from both parties have made empty promises which will soon become broken promises with painful consequences if we fail to act now."

He drew his biggest reaction, saying: "Our rights come from nature and God, not from government."

'Back to the economy'

Conservative leaders, increasingly anxious over the state of Romney's campaign, had urged him to pass over reliable - but not particularly inspiring - figures such as Rob Portman, Ohio senator, and Tim Pawlenty, former Minnesota governor, and instead go for Ryan.

Ryan is a favourite of the conservative Tea Party, an anti-tax, limited-government movement that helped Republicans take over the US House of Representatives in 2010.

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Charlie Wolf, a conservative political analyst based in the UK, told Al Jazeera that Romney’s choice of a running mate was a wise decision as it puts the economy "front and centre".

"And [the economy] is where Mr Obama ... just cannot win if you look at the debt he’s racked up, and you look at unemployment, the deficit," Wolf said.

"[Obama] has been trying his best to stay off the economy ... and now it firmly goes back to that topic."

Democrats are eager to pounce on Ryan's budget plan with its proposed cuts to programmes for the elderly - particularly in Florida, where many seniors live and which could be a crucial state in the November election.

Ryan's selection makes the Florida leg of Romney's bus tour an instant test for the new ticket.

Obama's campaign manager, Jim Messina, said in a statement that Ryan shares Romney's commitment to "the flawed theory that new budget-busting tax cuts for the wealthy, while placing greater burdens on the middle class and seniors, will somehow deliver a stronger economy".

Romney starts a bus tour on Saturday through four politically divided states that he needs to win in November: Virginia, North Carolina, Florida and Ohio.

Source: Al Jazeera and agencies