Representative Marjorie Taylor Greene, the Georgia Republican who often casts herself as the standard-bearer of MAGA politics on Capitol Hill, said a “genocide” is underway in Gaza, becoming the first member of her party in Congress to use the term as she condemned the humanitarian disaster unfolding there.

“It’s the most truthful and easiest thing to say that Oct. 7 in Israel was horrific and all hostages must be returned, but so is the genocide, humanitarian crisis, and starvation happening in Gaza,” Ms. Greene said in a social media post on Monday evening.

It was the strongest in a series of escalating statements she has made in recent weeks criticizing Israel’s conduct of the war and calling for action to end the suffering in Gaza. The stance is a clear break with the vast majority of Republicans in Congress, who have made unconditional support for Israel a hallmark of their foreign policy approach.

Ms. Greene’s comments were a direct rebuke of one Republican colleague in particular, Representative Randy Fine of Florida, who has drawn intense criticism for comments he made on social media last week calling the images of starving children in Gaza a campaign of “Muslim terror propaganda.”

“Release the hostages,” Mr. Fine wrote, adding, “until then, starve away.”

Mr. Fine, a first-term lawmaker who has been outspoken in Congress about his Jewish faith and staunchly pro-Israel views, made the remarks the same day that he was elevated to a seat on the House Foreign Affairs Committee, the influential panel that focuses on international policy.

Mr. Fine made his comments before President Trump said there was “real starvation” happening in Gaza and made commitments to offer additional support to increase aid.