NORFOLK, VA - AUGUST 11: Republican vice presidential candidate, U.S. Rep. Paul Ryan (R-WI) waves during a campaign rally in front of the USS Wisconsin August 11, 2012 in Norfolk, Virginia. Republican presidential candidate Mitt Romney announced Paul Ryan, a seven term congressman, as his presidential running mate. Ryan is the Chairman of the House Budget Committee and provides a strong contrast to the Obama administration on fiscal policy. (Photo by Justin Sullivan/Getty Images)
Mitt Romney's selection of House Budget Chairman Paul Ryan as his running mate stirred prompt conservative enthusiasm on Saturday while Democrats vowed to link Romney to less popular elements of the Wisconsin congressman's budget plans.
Romney introduced Ryan to voters at a rally this morning in Norfolk, Va., where he highlighted the ambitious budget proposals that have made Ryan a hero to Republicans -- and a lightning rod for liberals.
"With energy and vision, Paul Ryan has become an intellectual leader of the Republican Party," Romney said upon introducing his new No. 2. "He understands the fiscal challenges facing America: our exploding deficits and crushing debt - and the fiscal catastrophe that awaits us if we don't change course."
In picking Ryan, Romney satisfied the clamor in his party's base for a "bold" pick, which, for many in conservative circles, meant naming Ryan himself.
The pick was a direct effort at energizing the GOP base, with whom Romney has sometimes had a fractured relationship.
"This really energizes the ticket enormously," Bay Buchanan, an outside adviser to the Romney campaign, told NBC News.
Elected Republicans -- from Ryan's home-state governor, Scott Walker, to the other candidates Romney had considered as running mates -- likewise hailed the decision.
"Paul Ryan is a courageous reformer who understands our nation's challenges, has proposed bold policy solutions to solve them, and has shown the courage to stand up to President Obama and other Washington politicians trying to tear him down," said Florida Sen. Marco Rubio in a statement. Rubio was another favorite of conservatives to round out the ticket.
But Democrats moved quickly to tie Romney to the controversial proposals that Ryan has offered in his two years as chairman of the House Budget Committee.
"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," said Jim Messina, the campaign manager for President Barack Obama.
Messina charged Ryan with seeking to "end Medicare as we know it by turning it into a voucher system, shifting thousands of dollars in health care costs to seniors" -- a line of attack sure to populate Democratic talking points.
Democrats had found success in attacking Ryan's first budget for its Medicare proposals, helping them to win a special election in upstate New York that was transformed into a referendum on the Ryan plan.
Obama campaign releases have been peppered with references to the "Romney-Ryan" plan now for months, and Democrats expressed renewed optimism that Ryan's selection as Romney's running mate would have a similarly positive effect on their downballot fortunes.
"I think politically speaking, this choice is welcome news to the right wing of the Republican Party. It's essentially telling independent voters to take a hike," Maryland Rep. Chris Van Hollen, the ranking Democrat on the budget committee, told NBC News. "In that sense, I think it will help the president and other Democratic candidates win the middle."
Van Hollen and Ryan have struck up a rapport during their time together on the committee, and the Maryland Democrat noted that he likes his colleague very much personally. "It's not been a food fight," Van Hollen said of the committee's work.
Ryan's selection is almost certain to inject his budget plan into the center of the election, but Romney may take strides toward de-emphasizing thornier elements of those budgets.
Buchanan argued that Ryan's selection didn't represent a full embrace of the controversial budgets authored by the Wisconsin Republican the last two years.
"There's no question that while Mitt Romney certainly praised Paul Ryan for his budget, but the two of them do disagree in some areas as to how it should be done," she said Saturday morning. "It's not an embrace, line by line, of the Ryan plan. Mitt Romney has his own plan."
Of Democrats' near-certain onslaught against the new ticket based on Ryan's budget plan, Buchanan added: "What the Democrats do is their business, and we'll see if they're successful. We can't control what the Democrats do. They've accused Romney of murdering a man's wife, so they'll go to any extreme they want."
Michael O'Brien, NBC News