The battle for the White House is heating up, especially among Catholics here in North Texas.

Some complain a letter from the Dallas and Fort Worth bishops basically endorses John McCain and puts their immortal lives on the line, if they vote for Barack Obama.

Parishioners heading to noon mass at St Patrick's in downtown Fort Worth are aware of moral issues they'll consider in the voting booth.

For guidance, Bishop Kevin Farrell of Dallas and Bishop Kevin Vann of the Fort Worth Catholic diocese, issued a letter.

The bishops warn that "to vote for a candidate who supports the intrinsic evil of abortion or abortion rights when there is a morally acceptable alternative... would be to cooperate in the evil, and therefore, morally impermissible."

"If you want to be part of the Catholic Church, you have to adhere to those moral principles. It doesn't endorse any candidate," said Sean Toye, a Catholic worshipper.

But abortion is a big issue in the campaign.

Senator John McCain is strongly pro-life, favoring repeal of Roe v. Wade.

Senator Barack Obama supports abortion rights.

One worshipper did not take this as a directive on how to vote.

"I can make up my own mind independently," he said.

But the letter says the decision could affect an individual's salvation.

Some Catholics take that as a threat they won't go to heaven if they vote for Obama.

Scholars are divided on whether the letter crosses the line into politics.

Semi-retired TCU political science professor Dr. Ron Flowers teaches a class on church and state.

"I believe it's over the line, but just barely," he said.

"The law is they may not engage in electioneering and maintain a tax exemption."

A spokesman for the Fort Worth Catholic diocese says the letter is not intended to be political, and that the feedback so far is overwhelmingly positive.

E-mail jdouglas@wfaa.com.