The war in Iraq has reemerged as a central issue in the U.S. presidential election campaign. In recent days, Republican contender John McCain and Democratic candidate Barack Obama have exchanged verbal salvos over Iraq. VOA National Correspondent Jim Malone has a report from Washington.

Public opinion polls indicate the weakening U.S. economy has jumped ahead of Iraq as the top election issue.

But the presumptive Republican presidential nominee, Senator John McCain of Arizona, is doing all he can to remind voters about the stakes in Iraq.

McCain seized on remarks made this week by Democratic contender Barack Obama in his debate in Cleveland with rival Hillary Clinton.

Obama said while he favors a phased withdrawal of U.S. troops from Iraq, he would quickly send them back if al-Qaida re-emerged as a threat.

"If al-Qaida is forming a base in Iraq, then we will have to act in a way that secures the American homeland and our interests abroad," he said.

That statement brought a mocking response from McCain, campaigning in Texas.

"Al-Qaida already has a base in Iraq," he said. "It is called al-Qaida in Iraq."

Obama was quick to fire back at McCain during his own campaign swing through Texas.

"I have some news for John McCain, and that is that there was no such thing as al-Qaida in Iraq until George Bush and John McCain decided to invade Iraq," said Obama.

McCain has been a strong advocate of the Bush administration's military surge strategy in Iraq, which has resulted in a more stable security environment in recent months.

President Bush was asked about the Obama-McCain debate over Iraq at his Thursday news conference.

"I believe Senator Obama better stay focused on his campaign with Senator Clinton, neither of whom has secured their party's nomination yet," he said.

Obama's rival for the Democratic nomination, Hillary Clinton, has also promised to begin withdrawing U.S. troops from Iraq shortly after taking office.

But Clinton argues that her longer experience in the Senate and her tenure as First Lady during the Clinton administration give her an advantage over Obama.

"In this moment of peril and promise, we need a president who is tested and ready, who can draw on years of real-world experience working on many of the issues we now confront," she said.

The public has become somewhat more optimistic about the situation in Iraq in recent months as the surge effort has improved security.

Karlyn Bowman, who monitors U.S. public opinion at the American Enterprise Institute in Washington, says Iraq could work to McCain's favor in the general election.

"Americans still believe the war was a mistake and Bush gets very negative marks on handling it," she said. "Still, and perhaps surprisingly, John McCain leads Clinton and, separately Obama, by 14 percentage points in the new Gallup poll as the candidate who can best handle the situation in Iraq. At least at this point in voter's minds, Iraq is not an albatross for McCain."

McCain said earlier this week that his prospects of winning the general election are directly tied to his ability to convince Americans that victory in Iraq is worth the cost.