Continued from page 1

Mr. Trump said that, if he were president, he would warn OPEC to lower oil prices — or else. During his speech, he managed to press most of the buttons required for a candidate to satisfy the economic, national defense and social conservative strains in the GOP electoral coalition.

Mr. Trump’s appearance was the highlight of a day that featured several potential presidential contenders, including Rep. Michele Bachmann.

“This is about making Barack Obama a one-term president,” the tea party favorite said in her keynote speech opening the conference. “We’re all about winning in 2012.”

The Minnesota Republican didn’t say whether she planned to enter the race.

Mr. Gingrich, who hasn’t officially declared his candidacy, used his speech to criticize Mr. Obama’s policies as a “war on American energy” and propose replacing the Environmental Protection Agency with an Environmental Solutions Agency that he said would reward innovation, could help create jobs and increase national security.

Mr. Santorum, who lost in 2006 but is popular among anti-abortion activists and might run for president, claimed that Democrats were too eager to criticize their own country.

“Some see America as less than perfect or downright imperfect. … Well, I disagree with that,” Mr. Santorum said.

All three earned polite applause and standing ovations.

This article is based in part on wire service reports.