Former U.S. House Speaker Newt Gingrich said Monday he's seriously considering seeking the Republican presidential nomination and will announce his decision early next year.

Gingrich, 67, said he would focus on helping Republican candidates through the midterm elections in November, then decide in February or March whether to seek the GOP nomination.

"I've never been this serious," Gingrich said. "It's fair to say that by February the groundwork will have been laid to consider seriously whether or not to run."

Gingrich predicted President Obama would be a one-term president.

"I think he will replace Jimmy Carter as the worst president of modern times," Gingrich said. "He is a disaster. His principles are fundamentally wrong. The people he appoints are more radical than he is and less competent."

Gingrich has been mentioned as a possible 2012 presidential candidate along with other Republicans, including former vice presidential nominee Sarah Palin, Minnesota Gov. Tim Pawlenty and former Massachusetts Gov. Mitt Romney.

Gingrich had a long congressional career and was House speaker from 1995 to 1999. He was given much of the credit for the Republican takeover of the House in 1994 but abruptly resigned from Congress in 1998 after his party faired poorly in midterm elections. He was also reprimanded by the House ethics panel for using tax-exempt funding to advance his political goals.

Gingrich championed a family values agenda and spearheaded efforts to impeach Clinton for perjury over his affair with White House intern Monica Lewinsky. Gingrich later admitted having an extramarital affair of his own in 1998 with a former congressional aide, Callista Bisek. He married Bisek after divorcing his second wife, Marianne.

After leaving Congress, Gingrich created American Solutions for Winning the Future, a tax-exempt organization that promotes conservative causes. He acknowledged considering a White House run in 2007 and said he also thought about a run against Clinton.

Gingrich said he would return several times this year to Iowa, where precinct caucuses lead off the presidential nominating process. He said he planned to lay the groundwork for a campaign by working hard for Republicans in the midterm elections.