We begin here with mitt romney's choice for a running mate, wisconsin's consciousman paul ryan. The the story breaking today. The headlines in media. A bold, risky pick writes one newspaper. "Romney... See More
We begin here with mitt romney's choice for a running mate, wisconsin's consciousman paul ryan. The the story breaking today. The headlines in media. A bold, risky pick writes one newspaper. "Romney rolls the dice" says another. Tweeting the first images of the sign, the hot off the presses now being waved at the first stops at a team in virginia. Here they are, side by side, first thing in virginia. Ryan, a tea party conservative favorite. And while speaking today, ryan wasted no time taking on the president. The two boarding the bus together, tonight in that crucial battle ground of virginia and with the battle lines new newly drawn, we ask the big picture question tonight, beginning with the obvious one. Will romney's choice help or hurt romney's chances. Beginning with our political correspondent jon karl in virginia tonight. Jon? Reporter: David, that bus tour started here in virginia. One of those make or break states. But they believe with paul ryan on board, this is a brand-new race. Mitt romney went bold and got a little carried away in the moment. Jn me in welcoming the next president of the united states paul ryan -- Reporter: What was that? The next president of the UNITED STATES -- Reporter: Not long after ryan took the stage -- 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. Reporter: A conservative, a electrifying choice. It puts the slumping economy and skyrocketing deficits front and center. I hear some people say that this is just the new normal. higher unemployment. Declining incomes and crushing debt is not a new normal. Reporter: Ryan is the republican with a plan to slash government spending by trillions of dollars. Including politically dangerous changes to medicare, replacing it in part with private insurance. We will unite america and get this done. Reporter: To some republicans, ryan is a little too bold, too risky. When he first introduced his budget, only a handful of republicans supported it. We asked ryan about it last year. What do you say to the maybe weak-kneed republicans? It's not time to go wobbly. Regardless, this is a time for leaders to be leaders. Reporter: For romney, the ryan pick gives him an energetic 42-year-old partner. A numbers guy who can take on the president as he did at a republican conference two years ago. The spending bill that you've signed into law, the domestic spending has been increased by 84%. We'll have a longer debate on the budget numbers then, all right? Reporter: But last year, we saw bill clinton reach out to ryan saying he hopes democrats would not just attack his plan but try to work with him, too. I hope the democrats don't use it as an excuse to do nothing. My guess is it's going to sink into paralysis is what's going to happen. If you ever want to talk about it, give me a call. Yeah, I'll give you a call. Reporter: Republicans hope paul ryan will inject energy into the romney campaign. And on day one, anyway, it looks like he has. D? Sure sounds like it. Jon karl leading us off.
This transcript has been automatically generated and may not be 100% accurate.