For his first eight years in Washington, Jim DeMint was like most members of Congress – relatively quiet, fairly innocuous and pretty much unknown outside his state.

Over his final six years in the Senate, DeMint rocked national politics like an earthquake, gaining fame and notoriety that few lawmakers can claim.

Reveling in his nickname as “Sen. Tea Party,” the Greenville Republican rode that populist uprising, fueling it with his uncompromising, in-your-face opposition to nearly all manner of federal spending.

DeMint, who earlier this month said he will leave the Senate in January to head a conservative think tank, helped make “earmarks” a household word. He spearheaded the drive to impose the current bipartisan moratorium on that funding, steered by members of Congress. He also helped to elevate the rapidly rising federal debt from a troublesome issue to a national crisis.

Perhaps most lastingly for his legacy, DeMint became the Senate’s biggest fundraiser, raising millions to bankroll ultraconservative Senate candidates.

Some of his acolytes, including U.S. Sens. Marco Rubio of Florida and Rand Paul of Kentucky, now are rising Republican stars. Other DeMint protégés, including Christine O’Donnell of Delaware and Todd Akin of Missouri, went down in flames, losing winnable Senate seats to Democrats.

DeMint’s many admirers say he helped bring a new generation of leaders to Washington who are forcing their colleagues to get the country’s fiscal house in order.

His numerous detractors, among them some conservative commentators and prominent Republicans, say he cost the GOP a shot at regaining control of the Senate by backing unelectable renegades.

“Policy-wise, I don’t think there’s anything out there that has his name on it that he’s going to be known for, but he definitely made his presence felt politically,” said Jennifer Duffy, a Senate analyst with the widely read Cook Political Report. “History will treat his time in Washington as a mixed record.”

Simplifying complex issues: ‘Amnesty’

Employing his skills as a former marketing firm owner, DeMint was able to turn complex issues into catchy, short phrases that grabbed attention and galvanized his growing legion of supporters across the country.

His branding of a major Senate immigration reform bill as “amnesty” in 2007 helped rouse grass-roots opposition that contributed to its defeat.

But two years later, his vow to make an even bigger health-care measure into President Barack Obama’s “Waterloo” failed. The Democrat-controlled Congress passed the Affordable Care Act and, eventually, the Supreme Court upheld the law.

Despite their efforts to downplay their differences, DeMint and South Carolina’s senior senator, fellow Republican Lindsey Graham of Seneca, made their state a test site for the widening divide within the GOP, casting conflicting votes and taking different stances on spending bills, immigration, climate change, Supreme Court nominees and other key issues.

Emphasizing the need to follow clear conservative principles, DeMint rejected compromise and criticized the results that came from it, warring with his own GOP at times.

He criticized Republican President George W. Bush and a GOP-controlled Congress that increased spending, drove up the national debt and passed new big-government programs, including Medicare coverage of prescription drugs and the No Child Left Behind education law.