NORFOLK, Virginia - US Republican presidential candidate Mitt Romney on Saturday said he has selected Congressman Paul Ryan, 42, as his vice presidential running mate.

Romney, the presumptive Republican nominee, announced that he has tapped the House of Representatives Budget Committee chairman at an event in front of the retired battleship USS Wisconsin - coincidentally named for Ryan's home state.

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

Republican US presidential candidate Mitt Romney arrives to introduce U.S. Congressman Paul Ryan (R-WI) as his vice-presidential running mate during a campaign event at the retired battleship USS Wisconsin in Norfolk, Virginia August 11, 2012. [Photo/Agencies]

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

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.

The choice of Ryan will bring the debate over how to reduce government spending and debt to the forefront of the race for the White House.

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 Ohio Senator Rob Portman and former Minnesota governor Tim Pawlenty, and instead go for Ryan.  

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

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

Democrats are eager to pounce on that issue - 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.

Romney bonded with Ryan during the Wisconsin Republican primary battle last spring, when Ryan campaigned enthusiastically for the former Massachusetts governor.

For Romney, an outsider to Washington, Ryan would provide some expertise in dealing with Congress.  

But Ryan, a member of the House for 13 years and a Capitol Hill staffer before that, is a Washington insider without business or executive experience. That is in contrast to Romney, who has been critical of Washington insiders and says his years in private equity as a founder of Bain Capital have given him insight into the needs of US businesses.

Unlike many of his colleagues, who made their names at home and then came to Washington, Ryan got his start as a Hill intern and aide and then went back to Janesville, Wisconsin, to run for office, getting elected to Congress in 1998.  

He already had a passionate interest in the budget, joking in 2010 that it was "kind of weird" that he had been "reading federal budgets since I was 22 years old. I know that's kind of sick."

A Rapid rise

Ryan had begun work on a budget blueprint of his own before Republicans captured the House in the 2010 mid-term elections. But it got little attention from reporters or Republican colleagues, who had little interest in associating themselves with a detailed list of budget cuts.

By the fall of 2010, however, the budget - and the deficit - had become defining issues, thanks in part to the Tea Party movement.  

After Republicans took control of the House in January 2010, Ryan became chairman of the House Budget Committee. Suddenly he was one of the Republican Party's most visible and formidable leaders, and a frequent guest on cable news shows and the Republican speaking circuit.  

Ryan's budget plan, which passed the Republican-controlled House last March despite significant Democratic opposition, aims to cut tax rates while also slowing the rapid growth of the federal debt. It would do so mainly by cutting domestic programs that many Democrats have vowed to protect.

By choosing Ryan, Romney effectively adopts the Ryan budget, which includes proposed cuts to Medicare, the healthcare program for the elderly, long considered to be politically taboo.  

Ryan would set up a voucher-like system for the program to help beneficiaries buy private health insurance or give them access to the traditional fee-for-service plan.

Another controversial portion of Ryan's budget is a plan to reduce the cost of Medicaid, the federally backed healthcare plan for the poor, by turning it into a block grant program for states.

Several Democrats have said that among the potential running mates for Romney, Ryan was the one they would most like to face because of his budget proposals.