From John Kerry to the governors of Indiana and New Jersey, Roman Catholic politicians are being challenged by bishops in a new and tougher way this election season over their stance on abortion.

Some bishops have taken the radical step of declaring that officials who support abortion rights shouldn't receive Holy Communion, and one has even said he'd personally refuse Kerry at the altar.

Critics think such tactics are fraught with risks. The hierarchy could be seen as partisan, or morally suspect in the wake of the clergy sex-abuse crisis. A backlash could even hurt the anti-abortion cause, or boost Kerry.

Historian John McGreevy, author of "Catholicism and American Freedom," says the church is on new ground.

"The bishops have to figure out what they want to do, and Kerry needs to figure how to respond."

It's quite a change from the Catholic pride during the 1960 campaign of John F. Kennedy, the only Catholic president and the last church member even in position to win the White House.

Since the Supreme Court legalized abortion in 1973, the only Catholic on a major party ticket has been Geraldine Ferraro in 1984. Cardinal John O'Connor criticized Ferraro for her abortion stand, while then-New York Gov. Mario Cuomo defended Catholic politicians' choices — anticipating the debate of 2004.

This latest confrontation has been building for several years.

In 1998, a declaration from the U.S. bishops' conference said it's a "grave contradiction" for politicians to claim to be "credible Catholics" yet disagree with the church on a fundamental matter like "direct attacks on innocent human life." But that left open exactly what the church should do about it.

Then, last year, a Vatican doctrinal decree directed at Catholic politicians said a well-formed conscience forbids support for any law that contradicts "fundamental" morality, with abortion listed first among relevant issues. A second Vatican statement said it's "gravely immoral" not to oppose legalization of same-sex unions — another matter on which Kerry and the hierarchy disagree.

Bishop William Weigand of Sacramento, Calif., then upped the ante, saying then-Gov. Gray Davis should renounce support for abortion rights or have the "integrity" to "abstain from receiving Holy Communion."

The Vatican's Cardinal Francis Arinze, Archbishop Alfred Hughes of New Orleans and Archbishop John Myers of Newark, N.J., have since said the same without naming names, as has Kerry's own archbishop, Sean O'Malley of Boston.