President Trump on Wednesday denied telling the widow of a U.S. soldier killed by Islamic State-linked militants in Niger that her husband knew "what he signed up for, but I guess it still hurts."

Rep. Frederica Wilson, D-Fla., said she overheard the comment during a conversation on speakerphone Tuesday between Trump and Army Sgt. La David Johnson's widow, Myeshia Johnson, as they traveled together to meet Johnson's body in Miami.

Trump challenged Wilson's claim in a tweet Wednesday: "Democrat Congresswoman totally fabricated what I said to the wife of a soldier who died in action (and I have proof). Sad!"

White House spokesman Sarah Huckabee later said that the conversation was not recorded, but that "several people" were in the room when Trump spoke with Myeshia Johnson. Trump was "completely respectful," she said.

Earlier, Wilson defended her claim on Twitter.

"I stand my account of the call with @realDonaldTrump and was not the only one who heard and was dismayed by his insensitive remarks."

La David Johnson’s mother, Cowanda Jones-Johnson, confirmed Wilson's account of the conversation to The Washington Post.

"President Trump did disrespect my son and my daughter and also me and my husband," Jones-Johnson said.

Myeshia Johnson, who is six months pregnant with the couple's third child, was very upset after speaking with Trump, Wilson said.

“To me that is something that you can say in a conversation, but you shouldn't say that to a grieving widow," Wilson said. "Everyone knows when you go to war you could possibly not come back alive. But you don't remind a grieving widow of that. It's so insensitive."

More:Trump makes false claim that former presidents didn't call families of slain troops

Related:4th U.S. soldier dead after attack in Niger, U.S. officials say

Wilson told CNN after Trump's tweet that her press aide and other members of Johnson family also heard parts of the conversation.

"So the president evidently is lying, because what I said is true," she said. "I have no reason to lie on the president of the United States with a dead soldier in my community."

Later Wednesday, Trump again denied making the statement, telling reporters that Wilson knew he was right but didn't want to admit it.

That drew another tweet from Wilson: "I still stand by my account of the call b/t @realDonaldTrump and Myesha Johnson. That is her name, Mr. Trump. Not "the woman" or "the wife.'"

Wilson said Johnson could not remember everything Trump said, but felt that Trump didn't know her husband's name. "Now that's the worst part," Wilson said.

She added she was "livid" after the call.

"I asked them to give me the phone because I wanted to speak with" Trump, Wilson told CNN. "And I was going to curse him out."

She said a master sergeant in the car declined her request for the phone.

Wilson said the soldier's father was her student when she was an elementary school principal. La David Johnson was a student in a mentorship program Wilson started, and Wilson started a GoFundMe campaign to raise money for scholarships for his children. The campaign exceeded $400,000 by Wednesday.

Trump was widely criticized after he defended his slow public response to the deaths of the soldiers, falsely claiming that most of his predecessors never called the families of servicemembers killed in action.

Four soldiers were ambushed, shot and killed while on a reconnaissance patrol in the west African country on Oct. 4. They were serving in Niger as part of an operation to train local forces to combat the Boko Haram terror group, which has ties to the Islamic State and al-Qaeda.

Johnson, 25, was initially declared missing when French helicopters evacuated the soldiers following the attack. Nigerian military personnel later recovered his body at the scene.

Wilson questioned the air support and firepower the soldier's patrol was provided with for its mission. An investigation into the deaths is underway.

Contributing: Gregory Korte and Heidi M. Przybyla