WASHINGTON (Reuters) - Former House of Representatives Speaker Newt Gingrich's Republican presidential effort raised $808,000 in the third quarter but has more than $1 million in debt, his campaign said on Saturday.

Gingrich, who launched his candidacy in May to challenge Democratic President Barack Obama in the 2012 election, has called for a balanced budget as well as cuts in spending and corporate tax rates, ideas popular among conservative Republicans.

But he has struggled with low poll numbers and experienced an exodus of campaign staffers over the summer.

He ended the period with roughly $350,000 cash on hand, having spent over $770,000, his campaign said.

Gingrich's fundraising numbers for the quarter lagged far behind Texas Governor Rick Perry's $17 million and former Massachusetts Governor Mitt Romney's $14 million. Businessman Herman Cain, who is rising among Republicans in opinion polls, raised $2.8 million in the third quarter.

Gingrich's campaign expressed optimism about its outlook.

"Looking at every indicator, Gingrich has momentum going in to the fall and will be the alternative to the frontrunner," spokesman R.C. Hammond said in a statement releasing the figures.

Gingrich led the "Republican revolution" in 1994 congressional elections that brought his party to power in Congress with a series of pledges know as the "Contract with America." He then served as House speaker for nearly four years.

(Reporting by Eric Johnson and Kim Dixon; Editing by Peter Cooney)