Leaders in California have sharply denounced Donald Trump as “reckless” and “deranged” after the US president suggested Iran could “take out” Los Angeles and San Diego – two liberal cities in the blue state that has been a frequent target of his administration.

At a rally in ruby red Nebraska on Monday night, Trump told supporters that he hoped to see a “tremendous victory” in the fast-approaching November midterm elections. He then suggested high prices due to the war with Iran were a “small price to pay for keeping the world safe – keeping our country safe”.

“They can take out a city,” Trump said in Grand Island. “Let them take out Los Angeles. Let them take out San Diego.” The crowd applauded.

“It’ll be over very soon,” Trump said of the war.

The governor and the cities’ mayors quickly condemned the comments. “After sending the National Guard and Marines to occupy California, Donald Trump is now saying our foreign enemies should ‘take out’ Los Angeles and San Diego,” the California governor, Gavin Newsom, said on X. “He is deranged and dangerous.”

Newsom, a Democrat who has repeatedly clashed with Trump over his two terms, said from his press office account: “Let’s be clear: The President is advocating for an attack on 10+ million U.S. residents in two of America’s largest cities. This is not normal. None of this is. And we will continue to remind folks of that every day.”

Karen Bass, the mayor of Los Angeles, assailed the president for making what she called “irresponsible threats” that “could potentially compromise” the safety of America’s second-largest city.

“The role of a president is to protect the country, not to actively threaten it and encourage attacks on American lives,” she said in a statement.

Todd Gloria, the mayor of San Diego, said his city was “not collateral damage” in the president’s war. “We are not expendable. And we are never a “small price to pay,” he wrote on X “Keep our city out of your reckless war talk.”

San Diego, the nation’s eighth-largest city, is home to critical US military infrastructure.

Online, the comments – part of a rambling, nearly hour-and-a-half speech – set off a debate about what the president actually meant. Was it a crude joke about two blue cities or had he, accidentally perhaps, disclosed confidential intelligence about potential Iranian targets?

Some conservative activists argued that Trump, in his elliptical way of speaking, was referring to high gas prices when he argued that it was a “small price to pay”, and not the capacity of Iran to “take out” a US city.

The White House did not immediately respond to a request for comment.

US defence officials have previously stated that Iran currently lacks the capability to launch a direct missile attack on the US mainland.

Trump has argued in previous speeches that allowing Iran to develop a nuclear weapon would threaten US cities. In his last state of the union speech he claimed that Iran was working to build missiles that would “soon” reach US soil.

In Nebraska, where an unexpectedly close Senate race has rattled Republicans, Trump insisted that he was “doing great” and urged supporters to pretend like his name was on the ballot when the vote in November. But in California, where Steve Hilton, the Republican gubernatorial candidate endorsed by Trump, is seeking an upset, the president’s comments were unwelcome.

“Thirteen million Californians call LA and San Diego counties home,” said Xavier Becerra, the Democratic nominee for governor who has sought to take up the anti-Trump mantle carried by the outgoing Newsom. “Their lives are not a ‘small price to pay’ or a punchline for Donald Trump.”