WASHINGTON, United States (AP) — Donald Trump’s campaign called Wednesday for Hillary Clinton to apologise and fire senior campaign officials involved in an email exchange that Republicans condemned as “breathtaking anti-Catholic bigotry”.

The April 2011 email exchange details a brief conversation between current Clinton Communications Director Jennifer Palmieri and John Halpin, a senior fellow at the Center for American Progress, a Democratic think tank with close ties to the Clinton campaign and the Obama White House.

Halpin wrote that “the most powerful elements of the conservative movement are all Catholic” and described their positions as “an amazing bastardization of the faith”.

“They must be attracted to the systematic thought and severely backwards gender relations and must be totally unaware of Christian democracy,” Halpin wrote.

Clinton campaign chairman John Podesta was included in the email conversation but did not respond.

Palmieri, who was at the Center for American Progress at the time, responded that Catholicism “is the most socially acceptable politically conservative religion. Their rich friends wouldn’t understand if they became evangelicals.”

The exchange was revealed this week among thousands of hacked Podesta emails made public by Wikileaks. Podesta says the FBI is investigating the matter as part of a broader investigation into Russian hacking of democratic groups.

The comments sparked an outcry from the Trump campaign and its Republican allies who are eager to go on the offensive as Trump struggles with his own party. GOP leaders and many elected Republicans distanced themselves from their own presidential nominee after Trump’s sexually predatory language was revealed on video last week.

Campaigning Wednesday in battleground Florida, Trump said Clinton’s team had been “viciously attacking Catholics and evangelicals”.

“Anybody of religion, I really think you have to vote for Donald Trump,” he said.

Palmieri told reporters travelling with Clinton on Wednesday that she doesn’t recognise the hacked email, although she wouldn’t say explicitly whether she believes it had been forged. The Clinton campaign has noted that Russian hackers have been known to fake information, but the campaign has not pointed to a specific example of a hacked email being altered.

Trump allies, in a conference call organised by his campaign, compared the email exchange to the persecution of the Irish in the early 19th century.

“The Clinton campaign, when in private, expresses breathtaking anti-Catholic bigotry,” said American Conservative Union chairman Matt Schlapp.

The Center for American Progress released a statement that did not authenticate the email exchange, but said Halpin, a Catholic, “has spent his career advocating and fighting for the common good and improving the lives of all Americans as a key tenant of his Catholic faith”.