Four southern U.S. states are holding Democratic Party presidential nominating contests Tuesday.

Voters are going to the polls in Florida, Texas, Mississippi and Louisiana.

Senator John Kerry of Massachusetts has already all but wrapped up the Democratic nomination. But today's voting is seen as a chance to test his appeal in the south, where President Bush and other Republicans have enjoyed broad support.

A new Washington Post-ABC News opinion poll indicates that public support for President Bush's performance on the economy and the situation in Iraq has fallen to the lowest level of his presidency. Of those voters polled in a national sample, 39 percent support him on the economy, 46 percent support him on Iraq and just 30 percent support him on the budget deficit.

According to the opinion poll, 57 percent of Americans say they want the next president to steer the country on a different course. The survey indicates Senator John Kerry narrowly leading President Bush, 48 to 44 percent, with independent candidate Ralph Nader clearing 3 percent.

Mr. Kerry campaigned Monday in Florida, which Mr. Bush narrowly won in the 2000 presidential election. He told supporters he will not let political attacks distract him from the issues of jobs, health care, the economy and national security.

President Bush was in his home state of Texas. At a fundraiser in Houston, Mr. Bush criticized his likely opponent for introducing legislation eight years ago to cut intelligence spending.

The president says Mr. Kerry was willing to gut the intelligence services, which Mr. Bush says is no way to lead a nation in a time of war.

A spokesman for Senator Kerry's campaign called the comment misleading. He said the senator has long supported increased spending on intelligence, but voted against a budget increase the spokesman called "essentially a slush fund for defense contractors."