A dose of youth and fiscal conservatism for presidential candidate Mitt Romney's campaign.

Wisconsin Congressman Paul Ryan, shown here greeting supporters at Romney's side during a rally, joined him on the ticket Saturday.

The 42-year-old is expected to inject energy into the campaign and put the focus on government spending.

(SOUNDBITE) (English) REPRESENTATIVE PAUL RYAN (REPUBLICAN OF WISCONSIN), SAYING:

"Both parties got us in this mess. Both parties are going to have to work together to get us out of this mess. And the real problem, I would add Mr. Speaker, is the fact that we spend way more money than we take in. We have to address that."

The announcement in Virginia comes as Romney lags behind President Barack Obama in the polls ahead of crucial campaign stops.

Ryan is known for his proposed alternative to Obama's budget as House budget chairman, including vast cuts to government health programs for the elderly and poor.

His tough stance resonates with conservatives.

But Democrats will use the plan against the pair when the Romney campaign hits Florida on a bus tour that kicks off this weekend.