Romney and Ryan campaigned side-by-side before Wisconsin's primary back in April, creating speculation that Ryan could be a potential vice-presidential candidate should Romney get the party's nomination.
On election night, Ryan introduced Romney after the state of Wisconsin effectively delivered him the party's nomination.
Last week, Romney rallied supporters in Ryan's hometown of Janesville.
If there were any doubt that Ryan is on the so-called "short list" it was eliminated by an Associated Press photo that captured Ryan in a golf cart -- one of a select few invited to a Romney retreat in Utah where the VP finalists were thought to be interviewed.
"Congressman Ryan has really risen above the crowd and really sort of broken out of the pack, and almost become a brand name," UW-Milwaukee Professor of Governmental Affairs Mordecai Lee said.
Romney and Ryan seem to have chemistry -- on display when Ryan felt comfortable enough to play a prank on Romney on April Fool's Day. Romney thought he was about to rally a big crowd, but Ryan introduced him to an almost empty room.
The two seem to have a sort of back-slapping "bromance," and in addition, a shared conservative vision for the country.
"This is the perfect race for Paul Ryan. The economy is the only issue and he's sort of Mr. Economics," Lee said.
There is a downside, as Ryan's budget is highly controversial.
If Ryan should be selected, the campaign would likely instantly become a referendum on Ryan's plans, not Romney's.
Ryan's critics ran memorable ads in which a Ryan look-alike pushed an elderly woman off a cliff -- a metaphor for what Democrats say his budget would do.
"I think it's amazing the Republicans would want to ruin a national program to end Medicare. They want to dismantle Medicare and social security to pay for tax cuts for billionaires," Wisconsin Democratic Party spokesman Graeme Zielinski said.
Lee speculates that if Ryan were asked, he'd likely accept the vice-presidential candidacy.
"For Paul Ryan, this couldn't be a better scenario for a politician who is ambitious and who likes public policy," Lee said.
Neither the Romney campaign nor the Ryan campaign will comment on this issue at this time, but Gov. Scott Walker, who's name has also been floated as a potential vice presidential candidate weighed in, saying if any VP candidate comes from Wisconsin, it should be Ryan.