They don’t call him the Milk Dud for nothing, but right now, he is on a little roll.

Jim Oberweis made most of his fortune in the family business, a high-end dairy delivery service and chain of ice cream parlors in Illinois. And in the space of six years in the previous decade, he poured many gallons of his riches into five failed campaigns for high-profile positions — earning not only that enduring nickname, but also the enmity of Republican operatives and officeholders from Capitol Hill to Springfield, Ill.

Now Oberweis has launched his second act in American politics by winning two straight elections. He took an open state Senate seat in the GOP outer suburbs of Chicago in 2012, and last week he claimed the nomination to try and stop Senate Majority Whip Richard J. Durbin from winning a fourth term.

But virtually no one expects Oberweis to extend his winning streak come November. At best, his allies concede, his caustic rhetorical approach and willingness to tap his own bank account could combine to make the fall campaign more expensive and uncomfortable for Durbin. (The Democrat, who counts President Barack Obama as his proudest mentoring achievement, remains favored in a year when the president’s sagging approval is the defining dynamic nationwide.)

And at worst, losing a sixth high-profile election could doom the 67-year-old Oberweis to live with the ridicule that comes with the label “perennial candidate,” no matter what he ends up accomplishing after returning to the state legislature.

Oberweis spent a combined $4 million losing GOP primaries for the Senate in 2002 and 2004. Then he put $2.2 million more into a runner-up bid for the 2006 gubernatorial nomination. And then he threw $3.8 million at twin quests for the House in 2008, but was unable to hold what looked like a reliably Republican district in either the special or general elections after former Speaker J. Dennis Hastert resigned.

To be sure, getting to Congress after multiple unsuccessful forays has plenty of precedent. Thirteen current members won their first elections to the House on their third congressional try. Four more got to the Hill on their fourth attempt. And one veteran House member had to run five times to finally notch a victory: Democrat Collin C. Peterson, who last week announced his bid for a 13th term in a western Minnesota district that Mitt Romney carried two years ago. As a state senator, Peterson lost primaries in 1982 and 1988, and general elections in 1984 and 1986, that one by just 126 votes. He ultimately defeated a veteran GOP incumbent to gain his seat in 1990.

If he can defy all odds, Peterson’s is the record Oberweis would match this year. But few Republicans on either side of the party’s internal divide sound interested in taking the bet.

Not even a perfunctory word of praise for his primary victory was spoken by the National Republican Senatorial Committee. And tea party groups in Illinois bemoaned the loss of the other candidate, Doug Truax, a political neophyte and health care consultant who took 44 percent. (Among his endorsers were former Speaker Newt Gingrich and Illinois Rep. Aaron Schock, who both talked about the need for a fresh face to represent the moribund Illinois GOP.)

Partly, this is because Oberweis presents as a manifestly flawed candidate, even without the baggage that comes from being labeled an electoral retread. Two stories dominated coverage just before the primary: With a big snowstorm barreling across the Midwest, Oberweis spent much of the campaign’s closing week playing golf at his home on the Gulf Coast in southern Florida. And, after citing an increase in the rural highway speed limit from 65 mph to 70 mph as his main achievement as a legislator, the Chicago Tribune found he’d been ticketed for speeding 11 times since 1988.

Combine that bad press with the roster of incendiary comments that made headlines in his past campaigns — about such hot-button topics as abortion, gay marriage and illegal immigration — and it’s pretty clear Oberweis will need to spend millions of his own money trying to engineer a statewide image makeover in the coming months.

But he seems to have backed away from his lavish self-funding habits of the 2000s. Oberweis didn’t spend a dime of his riches (from the two investment banking firms he started, as well as the eponymous dairy enterprise) to become a state legislator, and he only loaned his current campaign $500,000 before the primary. (Still, that loan amounted to 70 percent of his campaign’s receipts.)

And beyond his perceived shortcomings as a campaigner, Oberweis’ down-the-line conservatism on both fiscal and social policy will add to his underdog status in Illinois, where successful GOP statewide candidates (Sen. Mark S. Kirk, most prominently) have positioned themselves near the center and where Obama, a former state senator himself, remains more popular than he is nationally.

Durbin, who won his first three Senate elections by an average of 25 points, is now 69 and may well be running his final campaign. He begins with $5.7 million in the bank and a reputation for paying remarkably dogged attention to home-state matters in light of the demands on his time as No. 2 in the Senate hierarchy.

All this has some Illinois Republicans worried that Oberweis, whose name will top the GOP ballot line on Nov. 4, could drag down the rest of the ticket. Most notably that’s the multimillionaire on whom the Republican Party has much more reason to stake its 2014 fortunes in the state: Bruce Rauner, who won the nomination for governor last week with a populist message about upending the status quo in the financially troubled Democratic state government with a more businesslike approach. Rauner spent $6 million of his private equity fortune to best three veteran politicians in the primary and will now oppose Gov. Pat Quinn’s bid for a third term.

The people controlling the party purse strings aren’t going to be pushing any of their largess toward Oberweis, given that they have many more viable ways to go after the six seats needed for a Senate majority — and given their many past frustrations with the candidate. “Never again,” was the crystal clear sentiment about Oberweis that national GOP kingmakers and plenty of pundits delivered after he squandered both his shots at the Hastert seat.

But that was six years ago, which is so many lifetimes in politics. And there is just so much the operatives can control when confronted with a robust mix of money, ego and determination.

IF AT FIRST YOU DON’T SUCCEED . . .

The CQ Roll Call members’ database shows 18 in the 113th Congress mounted multiple unsuccessful campaigns before finally winning a seat. See the graphic online here.