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Mitt Romney, after picking Wisconsin Rep. Paul Ryan as his running mate Saturday, charges into the final pre-convention stretch giving voters a much sharper picture of where his campaign stands as he hits the reset button on the race.

Ryan's selection ends months of speculation and puts in place the final piece of his campaign heading into the Tampa convention. It also leaves no doubt that the Republican candidate aims to run a campaign that draws a sharp contrast against President Obama on both the economy and the debt, considering Ryan's reputation as a budget slasher.

Within minutes of Romney announcing that Ryan, the House Budget Committee chairman, would be his running mate, the two men and their families boarded the campaign bus for a four-day tour of swing states Virginia, North Carolina, Florida and Ohio.

In two Virginia stops, an energized Romney called for an end to ugly campaign attack ads by the Obama campaign, while praising Ryan and hammering the president about his recent “You didn’t built that” comments regarding American small businesses.

“We took a step forward to restore the promise for America,” Romney said about Ryan, in Ashland, Va. “I selected a leader.”

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    Romney will face a tough challenge over the final months leading to the November election.

    His overseas trip that included stops in England and Israel received mixed reviews, and he has slipped several percentage points to Obama in recent polls.

    The choice in Ryan and his focus on a balanced budget also could help Romney return the election narrative from his tax returns and tenure at the Bain Capital private equity firm to the economy and Obama’s failure to significantly cut unemployment and bring other significant changes over the past three-and-a-half years.

    Democrats wasted no time Saturday in trying to foil that strategy -- attacking Ryan with a familiar and expected assault on his tough-love budget proposals, which Democrats suggest would help millionaires and hurt seniors.

    A clearly well-prepared Obama campaign led the attack, launching a website within minutes of Mitt Romney’s official announcement that called the House Budget Committee chairman’s budget proposals a “sham.”

    The website, “Mitt Romney-Paul Ryan: The Go Back Team,” cites five facts that voters “need to know” about Ryan.

    “Paul Ryan’s top-down budget plan is a sham,” reads the first entry.

    The Obama campaign by Saturday afternoon released its first video ad, a 94-second spot titled “Mitt Romney and Paul Ryan: Back to the Failed Top-Down Policies.”

    The Ryan announcement essentially puts the final chess piece in play for the upcoming GOP national convention. And Ryan will have a chance to square off directly against Vice President Joe Biden in an Oct. 11 debate at Centre College, in Danville, Ky.

    Democrats, in their rapid-fire responses Saturday, seemed eager to draw attention to Ryan’s balanced-budget plan, which they said would increase taxes on the middle class so millionaires can continue to get tax cuts. They also said Ryan’s conservative views are “out of touch with most Americans’ values” and would move the country backward on civil rights and women’s health issues.

    Ryan, a seven-term congressman, also wasted no time Saturday, attacking President Obama in his first speech after Romney had announced him as a running mate.

    "No one disputes that President Obama inherited a difficult situation,” Ryan said when introduced as the GOP vice presidential candidate, during an event at a Norfolk, Va., naval yard with the USS Wisconsin in the background. "Whatever the explanations, whatever the excuses, this is a record of failure."

    Obama campaign manager Jim Messina said the Romney campaign will try to portray the 42-year-old Ryan as a fiscal conservative whose House GOP-approved budget is an earnest attempt to scale back government and reduce the federal deficit.

    However, Messina warned that Ryan, with Romney’s support, will in fact try to “end Medicare as we know it and slash the investments we need to keep our economy growing the all while cutting taxes for those at the very top.”

    He also said Romney “doubled down on his commitment to take our country back to the failed policies of the past.”

    Leading Democrats used strikingly similar language in their first-round efforts to knock down Ryan.

    Senate Majority Leader Harry Reid said the Ryan pick shows Romney has “doubled down on his commitment to gut Social Security and end Medicare as we know.”

    Maryland Democratic Rep. Chris Van Hollen said the Ryan choice tells him “Mitt Romney is doubling down on an economic approach that helps people like Mitt Romney.”

    Maryland Democratic Gov. Martin O’Malley, a faithful Obama campaign surrogate, said the Ryan pick brings to the Romney candidacy “a strong commitment to end Medicare as we know it.”

    Ryan and Romney were greeted Saturday in Norfolk with chants of "USA, USA" from the energized crowd.

    Ryan also accused the Obama team of being "more worried about their next election than they are about the next generation."

    Ryan may continue pushing for a version of the budget proposal he reintroduced earlier this year. That proposal would overhaul Medicare and Medicaid and make other sweeping changes that Democrats have labeled as extreme. But Ryan has stuck by his proposal as the solution to an ever-growing deficit inflamed by out-of-control entitlement spending.

    In a dose of the tough-love approach for which Ryan's has become known, he said: "We promise equal opportunity, not equal outcomes."

    Romney called his new running mate a man of "steadiness" and "integrity" when introducing him. He also praised Ryan as an "intellectual leader" of the party who understands the toll the federal debt is taking on the country but is optimistic about the future.

    "He doesn't demonize his opponents,” said Romney, who at a campaign stop Saturday afternoon in Ashland, Va., called for an end to campaign attacks ads.

    Romney initially fumbled his introduction of Ryan. In the closing line of his remarks, he referred to Ryan as the "next president." Romney quickly returned to the podium to correct himself.