Rep. Jacky Rosen (D-Nev.) fired back at President Trump Donald John TrumpBiden on Trump's refusal to commit to peaceful transfer of power: 'What country are we in?' Romney: 'Unthinkable and unacceptable' to not commit to peaceful transition of power Two Louisville police officers shot amid Breonna Taylor grand jury protests MORE on Saturday after he dubbed her "Wacky Jacky" during a campaign speech in Nevada.

“The President is attacking me with lies and petty insults because I’m not afraid to stand up to him," Rosen said in a statement after the rally. "Dean Heller Dean Arthur HellerOn The Trail: Democrats plan to hammer Trump on Social Security, Medicare Lobbying World Democrats spend big to put Senate in play MORE has been a rubber stamp for Donald Trump in Washington, caving to the President’s divisive agenda at Nevada’s expense. This was Senator Heller’s reward for his loyalty.”

Rosen, who is challenging Sen. Dean Heller (R-Nev.) in this fall's midterm elections, was singled out by Trump during the Nevada state GOP convention.

"[Heller's] opponent wants to raise taxes," Trump said, to boos. "She wants to raise taxes, think of it. I mean, it's ridiculous. Should I mention her name?"

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Trump paused as the crowd cheered him on to reveal her nickname.

"I have a great nickname for her," Trump added. "Wacky Jacky. You don't want her as your senator."

Heller is considered to be vulnerable in his Senate race, with Democrats hoping to pick up his seat to help flip the Senate.

A Nevada Independent/Mellman Group survey from April showed Heller leading Rosen by just 1 point.