WASHINGTON: Some of former President Donald Trump's fellow Republicans on Sunday lashed out at him for saying he would not want to protect NATO members from a future attack by Russia if those countries' contributions to the defense alliance were lagging.

"This is why I've been saying for a long time that he's unfit to be president of the United States," former Republican presidential candidate Chris Christie said in an interview with NBC's "Meet the Press" program.

During a political rally on Saturday in South Carolina, Trump complained about what he called "delinquent" payments by some NATO countries and recounted what he said was a past conversation with the head of "a big country" about an attack by Russia on such countries.

"No, I would not protect you. In fact I would encourage them (Russia) to do whatever the hell they want. You gotta pay," Trump said he told the unnamed leader.

The remarks prompted rebukes from the White House, which called them "appalling and unhinged," as well as from other top Western officials.

The failure of many of NATO's 31 members to meet a defense spending target of at least 2% of gross domestic product has long been a source of tension with the United States, whose armed forces form the core the alliance's military power. NATO estimates have shown that only 11 members are spending at the target level.

Former South Carolina Governor Nikki Haley, who is Trump's lone remaining challenger for the 2024 Republican presidential nomination, said: "The last thing we ever want to do is side with Russia."

Interviewed on CBS's "Face the Nation," she added: "Don’t take the side of someone who has gone and invaded a country and half a million people have died or been wounded because of (Russian President Vladimir) Putin" in his war against Ukraine.

Republican Senator Lindsey Graham, a close ally of Trump's, told Reuters in a brief hallway interview that he disagreed "with the way he (Trump) said it," referring to the NATO remarks. Graham added: "Russia didn't invade anybody when he was president and if he's president again they won't."

Politico reported that Republican Senator Thom Tillis blamed Trump aides for failing to explain to the former president that the United States, as a NATO member, is committed to defending any member of the alliance that is attacked.

It also quoted Republican Senator Rand Paul saying Trump's remarks were a "stupid thing to say."

On a day in which the Senate was holding a rare weekend of debates over President Joe Biden's request for emergency aid to help Ukraine repel a nearly two-year-old Russian attack and Israel in its war with Hamas in Gaza, some Republicans defended Trump.

"Virtually every American president at some point, in some way, has complained about other countries in NATO not doing enough. Trump's just the first one to express it in these terms. But I have zero concern, because he's been president before," Senator Marco Rubio said in an interview with CNN.

Jason Miller, senior Trump campaign advisor, in a statement sidestepped the remark encouraging Russia to take on some NATO allies, saying: "Democrat and media pearl-clutchers seem to have forgotten that we had four years of peace and prosperity under President Trump," while leveling attacks against Biden.

On Capitol Hill, Democratic Senator Peter Welch told Reuters: Trump "normalizes belligerent behavior. But in fact he means it." (Reporting by Richard Cowan; Editing by Don Durfee and Stephen Coates)