Herman Cain’s swoon is becoming too painful even to rubberneck. The Gingrich pile-on is now in full swing. Mitt Romney remains the front-runner, in name if not in numbers. And the final candidate of the quartet locked in a tie atop the latest Iowa poll is lurking in plain sight, steadily gaining ground as his rivals burn up in the heat of the national spotlight.

Unlike Cain or Rick Perry, Ron Paul is a known quantity in Washington: a rumpled, professorial figure whose consistent lectures on the merits of libertarian politics and Austrian economics have found increasing favor in a fearful time. His followers are the most committed of any candidate’s, but the 76-year-old congressman’s esoteric lectures, vendetta against the Fed and anti-empire diatribes weren’t winning over new ones. For the second presidential cycle in a row, polls suggested his ceiling was about 12%.

That appears to be changing. In Bloomberg’s Iowa poll, Paul sits at 19%, a point behind Cain and slightly ahead of Gingrich and Romney. And another Bloomberg survey released Wednesday shows Paul pulling in 17% in New Hampshire as well, far behind Romney but comfortably in second place. In a Public Policy Polling survey this week, the Texas Congressman leads President Obama 48% to 39% among independent voters — the only Republican hopeful to earn that distinction.

Paul’s climb in the polls is in part a function of attrition: each time Republican voters finish their fling with a competitor, they turn their wandering eyes elsewhere, and there aren’t too many candidates left who have yet to enjoy a turn in the spotlight. Despite a second-place finish in Ames — and an unsurpassed straw poll game — Paul has plodded along largely unnoticed, despite an indefatigable schedule and a strong ground game in several early primary states. He received 89 seconds of question in last weekend’s CBS News debate on foreign policy, prompting the latest in series of screeds from his advisers about the liberal media’s bias.

Of course, plenty of Republicans harbor doubts about Paul as well. If you ask early-state GOP insiders which dark horse is the likeliest to emerge next, Paul is rarely the one they mention. Iowans tend to give a nod to Rick Santorum, whose lowly poll numbers belie the fact that he’s the lone GOP hopeful to plant his flag in each of the state’s 99 counties. In New Hampshire it’s generally Jon Huntsman, who has blanketed the state and this week finally got his Super PAC to shell out for a hefty ad buy.

But Paul’s jargon-laced speeches and focus on cutting the national debt and deficit dovetail nicely with the concerns of primary voters this cycle. While not a conventional candidate in mien or message, his advisers have tried to stress that he is as strong a candidate as any against Barack Obama. “Dr. Paul being in the top tier shouldn’t be news to anyone who has been paying attention,” his campaign manager John Tate wrote Wednesday in an e-mail to supporters.

He’s likely to stay there. While Cain and Gingrich seem perpetually primed for implosion, Paul — even if he remains a long-shot to win — appears to be gaining strength as the long campaign churns. If he can glide to strong finishes in Iowa and New Hampshire, he has as good a shot as anyone to emerge as the leading alternative to Mitt Romney. It’s a scenario that likely makes the Romney brain trust salivate. But if voters are intent on a candidate who is the antithesis of Romney rather than simply an alternative, they’d be hard-pressed to find a candidate who fits the bill better than Paul.