House Budget Committee Chairman Rep. Paul Ryan, R-Wis., speaks on Capitol Hill in Washington, Tuesday, July 10, 2012.
By NBC's Domenico Montanaro and Mark Murray
Three different sources close to the Romney campaign indicate to NBC News that Mitt Romney will announce House Budget Committee Chairman Paul Ryan as his vice-presidential running mate at tomorrow's campaign event in Norfolk, VA.
The announcement will be in front of the U.S.S. Wisconsin -- which just happens to be Ryan's home state.
With recent national polls showing Romney trailing President Barack Obama, Ryan is a bold pick. He would excite economic conservatives, and is considered one of his party's rising stars.
But his budget plan -- which would substantially transform Medicare and Medicaid -- is a lightning rod. In fact, Democrats argue that Ryan's selection marks an opportunity to highlight Ryan's desired changes to Medicare, which include giving future seniors a voucher or premium support to help pay for their health insurance. Under Ryan's plan, future seniors would have the choice of using the voucher/premium support to purchase private insurance or through Medicare's traditional fee-for-service model.
"We've spent 18 months trying to make House races about their plan for Medicare and Mitt Romney just did it for us overnight," said one Democratic operative.
Ryan had been the focus of intense VP speculation for the last few days. Washington economic conservatives -- including the Wall Street Journal editorial page and the Weekly Standard -- have pushed for his selection.
In addition, Romney told NBC's Chuck Todd on Thursday he was looking for someone with "a vision for the country," who "adds something to the political discourse about the direction of the country” -- a sign that he might make a bold pick in Ryan.
At 11:11 pm ET, the Romney campaign announced that it would be making its VP selection on Saturday. And as First Read reported earlier this week, the VP finalists were Ryan, former Minnesota Gov. Tim Pawlenty, and Ohio Sen. Rob Portman.
NBCNews.com's Mike O'Brien contributed to this report.