LOS ANGELES – President Obama wasn’t mentioned by name, but he was clearly the target Thursday as the nation’s Roman Catholic bishops began their “Fortnight for Freedom” campaign with a renewed attack on a federal mandate for private employers to provide free contraceptive coverage to workers.

The mandate, Archbishop William Lori of Baltimore told worshipers at a nationally televised Mass, “will force conscientious private employers to violate their consciences” by making them offer “reproductive services that are morally objectionable.”

The Catholic Church considers birth control a sin, and has strenuously fought the Obama administration and its Department of Health and Human Services over the rule, which goes into effect Aug. 1.

Churches are exempt from the requirement, but the Catholic bishops say the government’s definition of a church is too narrow and leaves out faith-based institutions such as charities, schools and hospitals that employ or serve mostly non-Catholics.

“Friends,” said Lori, speaking at the Basilica of the National Shrine of the Assumption in Baltimore “we must not allow the government — any government, of any time, of any party — to impose such a restrictive definition on our beloved church or any church.”

That the bishops’ protest has landed in the middle of a presidential race has been lost on no one, least of all the bishops, who have insisted that they aren’t taking a partisan stand — and that the timing was dictated by Obama, not the church.

The Fortnight for Freedom, in which Catholics are being urged to speak out about the mandate, runs through July 4. It includes a political-style ad produced by a new organization, the Catholic Association, led by a former spokeswoman for the National Right to Life Committee.

The ad, running on Fox News, depicts the Catholic faithful and makes the point that faith is practiced outside churches, not just in the pews. Although it doesn’t mention the president by name, it features a glowering photo of Obama and a narrator intoning, “We will defend our right to practice our faith, free from government coercion.”

It’s anybody’s guess whether the bishops’ efforts will hurt Obama politically.

“It depends on how you think the campaign is going to be run,” said the Rev. Thomas Reese, a Catholic priest who is a senior fellow at the Woodstock Theological Center at Georgetown University. “If the campaign is all about energizing the base and getting them to vote, who cares what the bishops think?”

If anything, he said, the issue could shore up support among those who see Obama standing up for women’s reproductive freedom.

On the other hand, he said, “if you’re going after the independent swing voter, many of whom are Catholic, it doesn’t help the administration to have the bishops say negative things abut Obama.”