HOUSTON -- On a campaign stop in Houston Thursday, GOP presidential hopeful John McCain said Democratic candidates are misquoting him on how long American troops would have to stay in Iraq.

But the war in Iraq wasn’t the only issue McCain tackled.

As he gears up for the Texas primary, McCain says he doesn’t plan to raise taxes.

“This is the worst time we could raise taxes,” McCain said.

With his nomination all but sealed, Sen. McCain spent much of his time throwing long distance jabs at his potential Democratic opponents, particularly on the issue of the war in Iraq.

“If we do what senators Clinton and Obama want, and that’s declare a date for withdrawal, al-Qaida will tell the world they defeated the United States of America.

McCain also expressed concern on the environment.

“I believe climate change is real.  I think it’s taking place,” McCain said.

McCain also took a few good natured jabs at himself.

“By the way, I was glad to see Nader is in the race. He’s older than I am,” said the senator.

McCain spoke to a packed house at Rice University’s Baker Institute, where the questions were at times pointed when it came to Iraq.

“You’ve previously stated we’ll stay in Iraq as long as we need to be there, be it 10, 20 or 100 years,” said a Rice University student.

The student had referred to McCain’s response at a New Hampshire town hall meeting in January, when he was asked about a comment President Bush had made about U.S. troops remaining in Iraq for 50 years.

A remark that McCain said had been distorted before he departed for the airport on his Straight Talk Express.

McCain also discussed one of the biggest challenges he faces among conservative voters, the issue of immigration.  In the past he’s favored finding a way to provide legal status for the nation’s current undocumented workers, but now he says his top priority is border security.