DYERSVILLEAs Sen. John F. Kerry (Mass.) campaigned across Iowa on Sunday with Gov. Tom Vilsack, widely reported to be on Kerry's vice presidential short list, both men dodged repeated questions about whether their joint appearance might be a preview of the Democratic ticket.

But even as he tried to avoid making news Sunday, Kerry broke new ground in an interview that ran in the Dubuque, Iowa, Telegraph Herald. A Catholic who supports abortion rights and has taken heat from some in the church hierarchy for his stance, Kerry told the paper, "I oppose abortion, personally. I don't like abortion. I believe life does begin at conception."

Spokeswoman Stephanie Cutter said that although Kerry has often said abortion should be "safe, legal and rare," and that his religion shapes that view, she could not recall him ever publicly discussing when life begins.

"I can't take my Catholic belief, my article of faith, and legislate it on a Protestant or a Jew or an atheist," he continued in the interview. "We have separation of church and state in the United States of America." The comments came on the final day of a three-state Midwest swing, during which Kerry has repeatedly sought to dispel stereotypes that could play negatively among voters there.

President Bush's campaign said these instances are further evidence of what it says is Kerry's propensity for misleading flip-flops.

"John Kerry's ridiculous claim to hold conservative values and his willingness to change his beliefs to fit his audience betrays a startling lack of conviction on important issues like abortion that will make it difficult for voters to give him their trust," said Steve Schmidt, a Bush campaign spokesman.

On Sunday morning, the day the candidate's abortion comments appeared in the local paper, Kerry sat in a church pew near Vilsack, also a Catholic who supports abortion rights, and his wife, Christie, one of Kerry's earliest backers in Iowa.

Afterward, several parishioners asked him about his position on abortion and his vote against a recent bill that would have banned the late-term procedure opponents call "partial birth" abortion, according to a reporter for the Telegraph Herald who sat behind Kerry's pew. Kerry replied that he would have supported the ban if it had included an exception for the health of the mother.

Kerry took Communion during Mass, which a few Catholic bishops have publicly said he should not do because of his abortion views.

"I wish he was against abortion, but I don't think that'll get settled," said Helen Willenberg, 83, a Catholic who met Kerry later in the day. "But I still hope he wins."

Later, Kerry and Vilsack walked the same Cascade, Iowa, parade route, shaking hands with voters, but rarely walking alongside each other or conversing publicly.

"Come on up here, Mr. President, we've got room for you," said a man seated on the porch of the Hughes Realty agency, as Kerry hopped over to say hello. There were also scattered Bush signs, some Bush stickers on folks holding Kerry signs and at least one heckler, in a T-shirt that read "W in '04," who yelled, "Kerry go home."

With speculation rampant Sunday, Kerry's daughter Vanessa told CNN that even she had tried but failed to get a hint from her father about his choice as running mate.

Asked whether he had decided who would join his ticket, Kerry said, "I made a decision to get a drink and eat some lunch." Afterward, the group proceeded to Dyersville for a photo opportunity on the spot where the 1989 movie "Field of Dreams" was filmed.

Surrounded by a half-dozen Little Leaguers with baseball gloves, Kerry ambled across the diamond into the thigh-high Iowa corn. As the children's heads disappeared, the 6-foot-4 senator ducked out of view, re-creating a scene from the movie, in which long-dead baseball players vanish after a game.

Kerry took a turn at bat, fielded ground balls at second base and pitched to an assortment of kids, and later to Vanessa Kerry, who, along with her sister, Alexandra, joined him on the campaign trail over the weekend.

At an evening barbecue at a home in Independence, Iowa, Kerry told about 200 supporters how happy he was to be back in the Hawkeye State. Kerry's comeback victory in the Iowa caucuses Jan. 19 propelled him to the front of the Democratic pack.

"I was being mentioned on the obituary pages here," he said, half-jokingly, before thanking those gathered for backing him and asking them to continue their support.