These days, you hear it everywhere — from Republican donors and veteran operatives, and at Capitol Hill watering holes. A few weeks ago, it was a wishful rumor floating in the Beltway ether. Now, sources close to the Romney campaign say it’s for real, that the taciturn former Massachusetts governor is quietly warming to the idea…

[B]ehind the scenes, Ryan’s stock has been steadily rising. Romney, a former Bain Capital consultant who relishes data and metrics, has clicked with the youthful Badger State wonk. They have campaigned together and speak frequently on the phone, comparing notes on policy and strategy. And earlier this year, with Ryan’s blessing, Romney hired three of Ryan’s Budget Committee advisers to help him in Boston…

Since [June], sources say, Ryan has slowly floated to the top of Romney’s vice-presidential shortlist. In conversations with senior advisers and donors — at the campaign’s summer retreat in Park City, Utah, and at his lakefront home in New Hampshire — Romney has repeatedly expressed his admiration for the Wisconsin lawmaker…

“If I had my druthers, I would hope Romney would pick one of the other options,” says Grover Norquist, the president of Americans for Tax Reform and a Ryan supporter. “The most important thing in the first year of a Romney administration would be a U-turn on the road to serfdom, and the way to do that is by passing the Ryan budget, which requires a major mover not just at the White House, but in Congress. It’d be easier to do that with Ryan in the House, since he has walked through it already with every Republican.”

In the most simple of terms, you can break down Romney’s choices for VP into two categories. There are the safe but less-than-scintillating picks (Portman, Pawlenty) and there are the rock-star-but-riskier picks (Florida Sen. Marco Rubio, New Jersey Gov. Chris Christie).

Ryan is the closest thing to a hybrid of those two categories. (You can make an argument here for Jindal but we tend to think Ryan trumps him on the “star” front.)

Ryan is someone who is well known and well liked by the party establishment, having served in Congress since 1998 and currently chairing the House Budget Committee.

At the same time, Ryan’s budget proposals over the last two years have turned him into a hero among national conservatives (and a villain among liberals, but more on that in the case against Ryan) and he is widely regarded as one of the major figures in the GOP.

[P]utting Ryan on the ticket would ensure that the presidential race is a contest of ideas, not just personalities. In a country where conservatives outnumber liberals two-to-one and where President Obama is thought to be more likable than Mitt Romney by huge margins (+30 according to USA Today/Gallup, +38 in the Washington Post/ABC poll), this strikes us as a good idea.

Of course Democrats will demagogue the entitlement reform proposals in Ryan’s budget. But they’re going to do that anyway. Romney and Republicans already own those reforms—97 percent of congressional Republicans voted for them, and Romney has embraced them without much qualification. “I think it’d be marvelous if the Senate were to pick up Paul Ryan’s budget and adopt it and pass it along to the president,” he said in early April. In late March he declared: “I’m very supportive of the Ryan budget.”

If Ryan’s budget is going to be a central part of the debate over the next three months, who better to explain and defend it than Paul Ryan?

Then comes governing…

There would inevitably be dissonance in Congress next year – even among Republicans and a Romney Administration. If push comes to shove over whether various initiatives do enough to reduce spending to satisfy the tea party – or if the GOP has to up the debt limit, no one will have more credibility in Republican ranks than Paul Ryan. If Romney stays in alignment with Ryan’s plan, the incipient president can dispatch Ryan himself to Capitol Hill to whip recalcitrant members. After all, most of them all voted for Ryan’s budget twice. Romney-Ryan wouldn’t necessarily be asking them to deviate from their track record…

The nation’s problems are fiscal. Managing a tea party-driven House Republican Conference is already a challenge to Republican leaders. If Mitt Romney’s calculus is the same, he could very well tap Paul Ryan to be his running mate.

But among non-political junkies, Ryan is hardly known at all. He’s viewed as just another member of Congress, a politically unpopular institution. Moreover, picking him would allow Obama to make the election a referendum over protecting the social safety net.

A disproportionate number of the undecided voters, according to polls and focus groups, are disaffected people who disapprove of Obama’s job performance but rely on government entitlements that Democrats vigorously defend. They don’t know much about the “Ryan budget” but they worry Republicans could take away their benefits. They’re inclined to vote Obama out of office, but a Romney-Ryan ticket could worry them enough that they’d vote for the devil they know.

Should [Romney pick Ryan], the Ryan plan would immediately become a far bigger part of the Romney campaign that it is now — it would, in fact, move to the top of the Romney agenda.

That’s something that unnerves a number of Republicans. They respect Ryan and the work he has done, but they worry that putting him on the presidential ticket would brand the Republican party as the party of austerity at a time when more voters are more concerned about job creation than budget cutting.

Of course, Democrats are going to bash Romney on spending cuts and Medicare reform regardless of what he does. Since that is inevitable, say Ryan supporters, why not put the plan’s most articulate defender, Paul Ryan himself, on the ticket? One reason would be that Mitt Romney has shown no inclination to make the Ryan plan the centerpiece of his campaign. Perhaps that’s what he’s planning — perhaps he planned all along to run on jobs until mid-August, only to pivot to entitlement reform for the rest of the campaign. But that’s not likely.

As speculation over whom Mitt Romney might choose as a running mate reaches a fever pitch, one of the Republicans rumored to be on the short list — Wisconsin Rep. Paul Ryan — is going on vacation.

Ryan told reporters here that he is taking his family to Colorado, beginning Saturday, for a weeklong trip during the summer congressional recess…

Meanwhile, speculation has grown surrounding just when Romney will name his No. 2 has grown; some believe it could come as early as this week. That, presumably, would take Ryan out of the equation if he maintains his current schedule and heads to Colorado.