Ryan, appearing at the beginning of a four-day, four-state bus tour in Norfolk, Virginia, moved quickly to position himself and Romney, the presumptive Republican presidential nominee, as champions of voters dissatisfied with the economy.
"I represent a part of America that includes inner cities, rural areas, suburbs and factory towns," he said Saturday morning, the U.S.S. Wisconsin in the backdrop. "Over the years I have seen and heard from a lot of families, from a lot of those running small businesses, and from people who are in need. But what I have heard lately, that's what troubles me the most. There is something different in their voice and in their words. What I hear from them are diminished dreams, lowered expectations, uncertain futures.
"I hear some people say that this is just 'the new normal.' Higher unemployment, declining incomes and crushing debt is not a new normal. It's the result of misguided policies. And next January, our economy will begin a comeback with the Romney plan for a stronger middle class that will lead to more jobs and more take-home pay for working Americans."
GOP sources told CNN on Friday that Sen. Marco Rubio of Florida, former Minnesota Gov. Tim Pawlenty and Sen. Rob Portman of Ohio had all been told that they were not getting the nod.
A campaign aide told CNN that Romney had made his decision August 1.
Paul Ryan, top GOP voice on fiscal matters
Romney, 65, initially flubbed his big line, announcing, "Join me in welcoming the next president of the United States, Paul Ryan!" He recovered moments later when Ryan took the stage, saying, "Every now and then, I'm known to make a mistake. I did not make a mistake with this guy, but I can tell you this: He's going to be the next vice president of the United States."
Romney called Ryan, 42, "a faithful Catholic" who "believes in the worth and dignity of every human life." He lauded the fifth-generation Wisconsin native serving his seventh term in Congress as "an intellectual leader of the Republican Party" and a person who will help lead the country "to widespread and shared prosperity."
Romney had called several of the candidates on his vice presidential shortlist on Friday evening to tell them he had selected a running mate and to thank them for assisting with his campaign, a Republican familiar with the calls told CNN. Romney did not indicate on the calls whom he had selected, the source said.
In a statement, Portman called Ryan "a great choice." He added, "I look forward to working closely with a Romney-Ryan administration to restore fiscal sanity and enact pro-growth policies to create jobs."
Accolades poured in from Republicans. In a statement, Senate Republican Leader Mitch McConnell called Ryan, the House budget chairman, "a confirmation that Gov. Romney is serious about strengthening America's economic future, tackling the deficits and debt that have skyrocketed under President Obama, and returning to a path to solvency and security."
Republican National Committee Chairman Reince Priebus said the new teammates "have the knowledge, expertise and vision we need to get America working again and get our fiscal house in order."
Pawlenty, in New Hampshire, called Ryan "a respected leader and a bold thinker regarding the changes needed to restore America."
But the Obama campaign was unenthused. "In naming Congressman Paul Ryan, Mitt Romney has chosen a leader of the House Republicans who shares his 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," it said in a statement.
"The architect of the radical Republican House budget, Ryan, like Romney, proposed an additional $250,000 tax cut for millionaires, and deep cuts in education from Head Start to college aid. His plan also would end Medicare as we know it by turning it into a voucher system, shifting thousands of dollars in health care costs to seniors. As a member of Congress, Ryan rubber-stamped the reckless Bush economic policies that exploded our deficit and crashed our economy. Now the Romney-Ryan ticket would take us back by repeating the same, catastrophic mistakes."
Communications staffers for the Romney campaign were ordered to report to their Boston headquarters at 8 a.m. Saturday, an unusual directive for a weekend, a Republican familiar with the plans told CNN.
There were other signals that Romney was ramping up for a splashy weekend: Much of the Romney high command flew Friday afternoon with the candidate from Boston to Norfolk, including Beth Myers, the adviser tasked with running the vice presidential search process, and Will Ritter, the campaign's director of advance who rarely leaves his spacious corner office in Boston's North End.
Democratic attacks on Ryan focus on changes to Medicare and Medicaid
Ann Romney, the candidate's wife, landed in Norfolk after her trip to the Olympic Games in London.
The bus tour will take Romney through major media markets in four battleground states -- Virginia, North Carolina, Florida and Ohio.
Virginia Gov. Bob McDonnell, once a potential running mate, introduced Romney. House Majority Leader Eric Cantor, a Richmond native, was set to join Romney at stops in the commonwealth on Saturday.