Mitt Romney's campaign formally announced that Rep. Paul Ryan (R-Wis.) would be his vice presidential pick early Saturday morning.
“Mitt's choice for VP is Paul Ryan. Spread the word about America's Comeback Team,” said a message from the campaign’s mobile phone app sent at 7:04 a.m. EDT.
A statement from the campaign confirmed the selection shortly after.
A GOP source told The Hill and several media outlets confirmed late Friday that Ryan would be named to the GOP ticket.
Romney formally announced Ryan's selection in Norfolk, Va., at an event at the USS Wisconsin.
"It is an honor to announce my running mate and the next vice president of the United States, Paul Ryan," he said.
Minutes after Romney made the announcement, Obama campaign manager Jim Messina released a statement criticizing Ryan's congressional record.
“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," Messina said. "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.”
Ryan will help solidify Romney's credentials with conservatives who have held some suspicions of the presumptive GOP presidential nominee, labeled a flip-flopper by opponents.
The fiscally conservative House Budget Committee chairman has long been a favorite of the right.
And in the past week, the chorus had grown louder in favor of Ryan. On Thursday, a Wall Street Journal editorial advocated for Ryan and the Weekly Standard also has pushed for him.
Ryan, 42, has been viewed as one of the top contenders for the No. 2 spot, though many thought that Romney would make a "safer" pick, such as Sen. Rob Portman (R-Ohio) or former Minnesota Gov. Tim Pawlenty (R).
Ryan appeared with Romney on the campaign trail and endorsed him shortly before the Wisconsin primary, which he went on to win. The two men spent several days campaigning together, and at the time observers commented on their obvious chemistry.
From there, the speculation began.
In May, Ryan showed off his attack-dog skills in a highly visible speech at the Reagan Library, where he repeatedly attacked President Obama, calling him “just another Washington politician.”
In June, Ryan was one of several possible vice presidential contenders who joined Romney on his bus tour, which was seen as a running mate tryout. Romney made one stop in Wisconsin on that tour — to Janesville, Ryan's hometown.
Wisconsin is one of 12 swing states that will be critical in determining the outcome of the 2012 election. Obama leads by 5 points there, according to the Real Clear Politics average, but the selection of Ryan turns the state into a toss-up.
A July survey from Public Policy Polling showed Obama leading Romney in Wisconsin 50 percent to 44 percent, but that lead shrinks to 47 to 46 percent with Ryan on the ticket.
A rising star in the Republican Party, Ryan became a nation figure with his budget proposal, which called for reducing the federal deficit almost entirely through spending cuts.
That budget blueprint could be Ryan's Achilles' heel, as Democrats, who hammered him on it in the past, are sure to do it again now that he's on the GOP ticket.
Ryan’s plan also includes a controversial proposal to revamp Medicare that would give future seniors the choice of opting out of the program in favor of private insurance. Democrats have seized on this point in particular, warning voters that it will “end Medicare as you know it.”
Romney was an early supporter of Ryan's budget plan.
Obama, speaking at an Associated Press luncheon in April, criticized the Ryan budget plan, saying, "They proposed a budget so far to the right that it makes the Contract With America look like the New Deal.”
That was the same event where Obama first attacked Romney by name, citing his GOP rival's support for Paul's plan: “He even called it ‘marvelous,’ which is a word you don’t often hear when it comes to describing a budget.”
On Saturday morning, Democrats were blasting their glee at Romney's decision.
"I haven't been this happy waking up since I was 12 and got a BMX for Christmas," said one top Democrat who works for an outside group which is helping to reelect Obama. "The Romney-Ryan plan is a complete crystallization of the two visions for this country. The Republicans-tax cuts for millionaires and ending Medicare as we know it and the Democrats- growing a strong middle class."
A former senior administration official agreed.
"I think we're all licking our chops this morning," the former official said. "The president has spent the last several months attacking the Republican budget and who better to be the VP pick than Ryan? Fits into our narrative in the best possible way."
But another former senior administration official said the Ryan pick is a significant step up from the last Republican VP pick- former Gov. Sarah Palin and could help Romney.
"They got someone well-spoken who doesn't inherently scare the crap out of everyday Americans... relative to their last pick, it's brilliant," said the former senior administration official.
Conservatives praised the pick.
Tea Party Express Chairwoman Amy Kremer said "selecting someone like Paul Ryan, who is so popular with tea party activists, proves that Mitt Romney is committed to addressing the economic issues that have been troubling our nation for the last four years."
Earlier this year, the U.S. Conference of Catholic Bishops criticized Ryan's budget for cutting food stamps and other assistance programs for the poor after Ryan said his Catholic faith helped shape the policies in the document.
Ryan, who is serving his seventh term in the House, voted for the Emergency Economic Stabilization Act of 2008, which created the Troubled Asset Relief program. He also voted for the auto bailout.
In 2010, Ryan voted against the DREAM Act, which is strongly backed by the White House and many Hispanic groups.
The selection of Ryan suggests Romney sees his path to victory through the Midwest instead of the Southwest, where the Hispanic population is larger. Obama enjoys a huge lead over Romney among Hispanics.
First elected to the House in 1998, Ryan is also popular among his fellow congressional Republicans. One of the GOP "Young Guns" in the House, he helped get several Republican lawmakers elected in 2010, which is when the party retook control of the lower chamber.
He is married to Janna Ryan, and they have three children.
Ryan will be the first House member selected as a vice presidential candidate since Walter Mondale (D) tapped then-Rep. Geraldine Ferraro (D-N.Y.) in 1984.
— Megan Wilson, Bob Cusack and Amie Parnes contributed to this report.
This story was published at 1:46 a.m. and has been updated.