Sen. Jim DeMint (R-S.C.), who has bucked the establishment to support tea party candidates, said Sunday that his party is “dead” if it wins a majority this fall and doesn’t stick to conservative principles.

Republicans held majorities in both chambers, and George W. Bush was in the White House when DeMint moved from the House to the Senate in 2005. But he said the party didn’t live up to its promises.

“Republicans didn’t do what we said we were going to do,” he said Sunday on CNN’s “State of the Union.” “We spent too much, we borrowed too much. And frankly, if we get the majority again, even if it’s just in the House, and we don’t do what we say, I think the Republican Party is dead.”

When asked about his declaration last week that electing conservative candidates is more important than winning a majority, he said the important thing is spending. “Let me clarify what I mean by conservative,” he said. “I’m just talking about common-sense people who don’t think balancing a checkbook is a radical idea. That’s what we’re looking for now, because the people in Washington have clearly gotten out of control in both parties.

“The quickest way to a majority, the quickest way to 60 votes in the Senate, is to have Republicans who stand on principle,” he added. “Nothing right wing; what I’m talking about is where mainstream America is, and it’s just common sense.”

He conceded that the chances of winning a majority in the Senate in 2010 “may not be that great,” but he deflected the criticism that his support for primary challengers against GOP incumbents was hurting the party’s chances in November.

“The only reason we have a chance at a majority now is a large part for the candidates I’ve been supporting. … If the Republican Party in the Senate was now symbolized by Arlen Specter and Charlie Crist, we would not have the energy behind our candidates anywhere in the country.”

Pennsylvania’s Specter switched from the Republican to the Democratic Party in 2009 in the hope of improving his chances at re-election to the Senate in 2010, but he lost in the primary this year. Crist, the governor of Florida, left the GOP this year to run for the Senate as an Independent when polls showed he trailed tea party favorite Marco Rubio, who became the Republican nominee.

Thinking ahead to the presidential election in 2012, DeMint said he’s looking for “a combination of Ronald Reagan and Winston Churchill, and I know he or she is out there somewhere.”