St. Cloud, Minn. ? President Bush pressed hard Thursday to undermine Democrat John Kerry as a prospective commander in chief, accusing the Massachusetts senator of waffling on Iraq and sending dangerously misleading signals to friend and foe alike.

Kerry, addressing National Guard veterans in Las Vegas, said it was Bush who was trying to persuade voters with “a fantasy world of spin” rather than telling the truth on Iraq.

“Mixed signals are the wrong signals to send to our troops in the field, our allies and, most of all, our enemies,” Bush said at a rally at a minor-league baseball field in St. Cloud as he campaigned through parts of Minnesota by bus.

Bush also kept up his criticism of Kerry’s health care proposals, saying they would create a multibillion-dollar government enterprise that would restrict choice and drive private companies out of business.

The president campaigned in a state that Democrat Al Gore carried in 2000 and where Kerry is ahead in recent polls — but one that GOP strategists consider highly competitive.

While Kerry addressed the same National Guard convention in Las Vegas that Bush had spoken to two days earlier, the president in Minnesota hammered at a favorite theme: that Kerry had continually changed positions on the war in Iraq.

Kerry said the problem was Bush’s approach and failure to own up to the seriousness of the situation in Iraq.

He told the National Guard Association of the United States: “I believe you deserve a president who isn’t going to gild that truth or gild our national security with politics, who is not going to ignore his own intelligence, who isn’t going to live in a different world of spin, who will give the American people the truth, not a fantasy world of spin but a world where we challenge our brave men and women to be able to meet the test of our times.”