(The Hill) – Former President Donald Trump on Monday tore into Sen. Mike Rounds after the South Dakota Republican rejected Trump’s baseless claims about the 2020 presidential election. 

In a lengthy statement, Trump rehashed his false assertion that the 2020 election was tainted by widespread fraud and vowed to withhold his support from Rounds the next time the South Dakota senator is up for reelection in 2026.

“Is he crazy or just stupid?” Trump said in the statement. “The numbers are conclusive, and the fraudulent and irregular votes are massive. The only reason he did this is because he got my endorsement and easily won his state in 2020, so now he thinks he has time, and those are the only ones, the weak, who will break away. Even though his election will not be coming up for 5 years, I will never endorse this jerk again.” 

Multiple state-level audits and reviews of the 2020 election have failed to produce proof of Trump’s claims, which have become a rallying point for his voter base in his post-presidency. 

Trump also dubbed Rounds a “RINO” — Republican in name only — before once again saying that he will not endorse the senator again.

“The Radical Left Democrats and RINOS, like ‘Senator’ Mike Rounds, do not make it easy for our Country to succeed,” Trump said. “He is a weak and ineffective leader, and I hereby firmly pledge that he will never receive my Endorsement again!”

The former president’s remarks came a day after Rounds said during an interview on ABC’s “This Week” that the 2020 election was, indeed, fair and noted that multiple reviews of alleged instances of fraud established that President Joe Biden’s victory was legitimate.

“While there were some irregularities, there were none of the irregularities which would have risen to the point where they would have changed the vote outcome in a single state,” Rounds said.

“The election was fair — as fair as we’ve seen,” he added. “We simply did not win the election as Republicans for the presidency.”

Trump’s false election claims have become something of a litmus test for Republicans, with the former president lashing out at any GOP official or candidate who breaks with him on the issue. 

He has already vowed to campaign against a handful of Republicans who have rejected his position on the 2020 election, including Sen. Lisa Murkowski (R-Alaska), who was one of seven GOP senators who voted last year to convict Trump in his second impeachment trial for his role in inciting the Jan. 6, 2021, riot at the U.S. Capitol.