Washington ? President Bush has spent about $40 million in campaign ads in recent weeks aimed at defeating Democrat John Kerry, but the president has problems of his own: growing doubts about Iraq and worries about the economy.

The two remain locked in a very close presidential race, an Associated Press poll found.

Bush was backed by 45 percent of voters and Kerry by 44 percent in the poll conducted by Ipsos-Public Affairs. Independent candidate Ralph Nader had 6 percent support. The numbers are essentially unchanged from AP-Ipsos polls taken in early and mid-March.

In one development that is potentially troublesome for Bush, a growing number of people think the Iraq situation is making the threat of worldwide terrorism worse.

Asked whether the military action in Iraq has increased or decreased the threat of terrorism around the world, half in the poll, 49 percent, said it had increased the threat, while 28 percent said it had decreased the threat.

The number of people who thought the Iraq situation increased the terrorism threat grew slightly from Monday through Wednesday at a time that television news was showing the sharply increasing violence in Iraq.

In a mid-February AP poll, Americans were evenly divided on the effects of military action in Iraq, with 38 percent saying it had increased the terror threat and the same number saying the threat had decreased.

The new poll found that 41 percent approve of Bush’s performance on foreign policy issues and 51 percent approve of his handling of the war on terrorism. His standing with the public on those issues has dropped since January.

“I would like if there was a better challenger for Bush,” said Justin Tucker, a 21-year-old college student from Prosser, Wash., who supports the president. “I just don’t believe in ripping the president out of office during a war on terror — especially to replace him with Kerry. Who knows what Kerry’s going to do?”

The public’s view of Bush’s handling of the economy was unchanged since March after signs last week that the jobs picture is improving. More than half in the poll, 53 percent, disapproved of Bush’s handling of the economy.