Updated

South Carolina Republican Sen. Jim DeMint unexpectedly quit Congress this winter, saying essentially that he could better advance the conservative cause as president of the Heritage Foundation think tank than in Congress.

Roughly eight months later, DeMint has no doubt pressed Congress, and House Republicans in particular, to take a conservative stance on such issues as the Farm Bill and President Obama’s health care law.

Heritage and DeMint won at least a partial victory on the recent Farm Bill vote, getting the House to split funding for food stamps from the rest of the bill but saying more reform is needed on the billions being spent on crop subsidies and other programs. And votes of sequestration, the debt limit and immigration are also on the near horizon.

But DeMint’s biggest challenges to date appears to lie in the weeks ahead when Congress returns in two weeks to vote on a temporary spending bill, which DeMint hopes will not include money for ObamaCare.

“We know that ObamaCare is unfair,” DeMint has said repeatedly over the past few months, as dismantling the law has emerged as a primary focus. “It’s unaffordable, unworkable and very unpopular. And this might be our last chance to stop it. … This is an urgent matter.”

Democrats and Republicans will try to agree before Oct. 1 on the temporary spending bill that funds federal agencies, with the possibility of a government shutdown should the sides fail to reach a deal.

DeMint is trying to put the specter of a shutdown on Obama, saying the president will be to blame should he insist on keeping his “flawed law” on the negotiating table.

Others in the Tea Party movement such as Kentucky Republican Sen. Rand Paul have said the GOP -- by controlling one-third of government with the House majority – has an obligation to challenge the bill, then hope for a House-Senate compromise.

However, the Democrat-controlled Senate will likely never agree to the so-called “defunding” of ObamaCare, nor would the president sign such an agreement, which would give DeMint little more than a symbolic victory.

“It’s an uphill battle unless the people in the country speak up,” DeMint acknowledged to Fox News on Friday, at about the midway point of Heritage Action for American’s nine-city Defund ObamaCare Town Hall Tour.

DeMint, a tour speaker, acknowledges that trying to put the onus on Obama has peril but thinks Americans are behind him, based on polls.

“There’s a risk in any kind of showdown with the president,” he told Fox. “But when do Americans not fight for what’s right because they are afraid they might lose?”

DeMint has gotten support from his closest allies for this efforts so far at Heritage, where he officially began this spring, and for his ObamaCare effort. Among those supporters are Arizona Republican Rep. Trent Franks and Texas Republican Sen. Ted Cruz, who joined DeMint on the tour.

“The fight to defund ObamaCare isn’t just a test for Heritage,” Franks told FoxNews.com. “It’s a test for the entire conservative movement and Republican Party.”

Franks, who has a 98 percent rating on Heritage Action's scorecard, also said DeMint is the “right fit” for the job at Heritage, a leader in the conservative movement, and that DeMint’s business experience makes him much more than “just a policy guy.”

The Main Street Partnership, a group of more moderate Republicans that has occasionally not seen eye to eye with DeMint, would also like to see the end of ObamaCare, but not to the point of a government shutdown. And it thinks the outcome of the fight could define DeMint’s early tenure.

“Actually, I have been pleasantly surprised by the calm manner that DeMint has displayed,” group president and former Ohio Republican Rep. Steve LaTourette told FoxNews.com. “But September and October are going to be huge months for the Congress, and DeMint's role in making something happen or fall apart will set his reputation.  … I worry every day that Republicans will charge ahead to a shutdown. ObamaCare will implode on its own, and the only thing that can save it is Republican overreach.”

Heritage and DeMint have not been supporters of House Speaker John Boehner, R-Ohio, and others whom they think have failed to follow conservative principles, most recently on votes on the Farm Bill and the Violence Against Women Reauthorization Act, for example.

Boehner, who got a zero on the scorecard, and essentially none of the other congressional Republicans who scored below 34 percent would comment for the story. Boehner in fact has no score because he didn't vote enough to get a rating, according to Heritage Action.

DeMint made clear Friday that Heritage “doesn’t get involved in elections.” But with the 2014 midterm elections fast approaching, he has the reputation as a candidate kingmaker, prompting the website BuzzFeed to suggest six members of Congress seeking reelection “may do well to start looking over their shoulder.”