Donald Trump has been forced to address a "sexist" remark made at the end of his victory speech on Tuesday night, in which he accused Hillary Clinton of playing the "woman's card" to win votes.

While the Republican presidential frontrunner was celebrating sweeping victories in five primaries, he took the opportunity to mock the qualifications of the Democratic candidate, suggesting she was playing "the woman's card" to her advantage in the presidential race.

"And frankly, if Hillary Clinton were a man, I don't think she'd get five per cent of the vote," Trump said during a news conference at Trump Tower. "The only thing she's got going is the woman's card. And the beautiful thing is, women don't like her."

Mary Pat Christie, the wife of New Jersey Governor Chris Christie, was standing behind Trump during his speech and had possibly the best reaction of all.


Unfortunately, her husband has already endorsed him and is even tipped as a potential running mate.

The Clinton campaign responded on Wednesday morning with an online video showing footage of the former secretary of state firing back at Trump's comments on her gender. "Mr Trump accused me of playing the quote 'woman card.' Well, if fighting for women's health care and paid family leave and equal pay is playing the 'woman card,' then deal me in," she told supporters at her victory party in Philadelphia.

Clinton - who also won big on Tuesday night with victories in four out of five Eastern states - seized the moment on Twitter immediately after Trump's speech.

Doing the rounds on television on Wednesday morning, Trump defended his remarks and dismissed critics who labelled him "sexist".

"It's not sexist, it's true. It's just a very, very true statement. If she were a man, she'd get five per cent. She's a bad candidate. She's a flawed candidate," he said on ABC's Good Morning America.

Appearing on MSNBC's Morning Joe, Trump said: "I haven't quite recovered, it's early in the morning, from her shouting that message. And I know a lot of people would say you can't say that about a woman because, of course, a woman doesn't shout, but the way she shouted that message was not - ooh.

"I guess I'll have to get used to a lot of that over the next four or five months."

Taking the opportunity to clear up recent speculation that he will undergo a makeover to reshape his image, Trump told CNN: "I'm not going to be changing. I'm presidential anyway." He also repeated his assertion that Clinton is "playing the woman card left and right".

Democratic presidential candidate Hillary Clinton addresses supporters in Philadelphia after winning the Pennsylvania state primary. Photo / AP
Democratic presidential candidate Hillary Clinton addresses supporters in Philadelphia after winning the Pennsylvania state primary. Photo / AP

It's not the first time Trump has suggested that Clinton's gender is behind her success. In January, the businessman took a shot at his rival during a televised interview with CBS's Face the Nation. "She's constantly playing the woman card. It's the only way she may get elected ... Personally, I'm not sure that anybody else other than me is going to beat her. And I think she's a flawed candidate."

"She's pandering to the public and she's pandering to women," he added.

Meanwhile, fans of the former first lady were left wondering how they could acquire their very own "woman's card" and #womancard quickly started trending on Twitter in New York.

After Tuesday's wins, both Clinton and Trump found themselves a giant step closer toward securing their parties' presidential nominations.

Demolishing his rivals Ted Cruz and John Kasich in Connecticut, Delaware, Maryland, Pennsylvania and Rhode Island, the real estate mogul declared to his supporters: "I consider myself the presumptive nominee. It's over. As far as I'm concerned it's over."

Barring a dramatic turn of events, Clinton has now cleared the way to become the Democratic nominee in the November election, which would make her the first woman in US history to reach that milestone.