Republican presidential front-runner Donald Trump is taking aim at Hillary Clinton after the Democratic front-runner referred to the real estate mogul as "sexist." Clinton was responding to a question about Trump's use of a vulgar term to describe her 2008 primary loss to Barack Obama.

Trump issued a warning on Twitter, telling Clinton to "be careful as you play the war on women or women being degraded card." He later tweeted, "I have great respect for women" and again warned her to "BE CAREFUL!"

The Hillary Clinton staged event yesterday was pathetic. Be careful Hillary as you play the war on women or women being degraded card. — Donald J. Trump (@realDonaldTrump) December 23, 2015

Hillary, when you complain about "a penchant for sexism," who are you referring to. I have great respect for women. BE CAREFUL! — Donald J. Trump (@realDonaldTrump) December 23, 2015

Clinton and her team don't seem too concerned about Trump's warnings, reports CBS News correspondent Julianna Goldman. Unlike Trump's Republican rivals who have struggled to confront him, Clinton is playing offense and urging their supporters to step up and express their displeasure with the real estate mogul's choice of language.

"I don't know that he has any boundaries at all," Clinton said in an interview with the Des Moines Register Tuesday.

Clinton said Trump should be held accountable for his language.

"I think he has to answer for what he says ... it's not the first time he's demonstrated a penchant for sexism. And so, I'm not sure, again, anybody's surprised," she said.

Trump fired back Wednesday night.

"I really haven't gone after Hillary yet and there's a lot to go after," Trump said

And so did his political director, Michael Glassner.

"I think it's ironic that Hillary Clinton is playing the sexism card considering the record of her husband and his term in the White House. He was impeached by the House of Representatives for his behavior," Glassner said on CNN.

Earlier this week, Clinton's staff urged supporters to use the campaign's hashtag #imwithher to combat Trump's "degrading language."

They're also capitalizing on one of Trump's few polling weaknesses.

A recent survey shows 61 percent of women nationally have an unfavorable opinion of Trump, including nearly 30 percent of Republican women.

"We run in the general election against the bipartisan corruption of Washington that Hillary Clinton embodies, that's how we win," Sen. Ted Cruz said while campaigning in Oklahoma.

Cruz continued his attacks on Clinton while his campaign fundraised off a widely condemned Washington Post cartoon that depicted his young daughters as trained monkeys.

"All of us learned in kindergarten, don't hit little girls," Cruz said.

A rare issue where Cruz showed kindness to his Democratic frontrunner.

"Don't mess with our kids. Don't mess with my kids. Don't mess with Marco's kids. Don't mess with Hillary's kids. Don't mess with anybody's kids," Cruz said.

There's about six weeks before the Iowa caucuses, and the candidates will be taking a few days off the trail for the holiday. But it's unclear if that also applies to social media, so we'll have to see if these fights make their way into or Twitter feeds this holiday season.