Presidential candidate Sen. Cory Booker (D-NJ) said if President Trump continues his attacks against former Vice President Joe Biden with regards to Ukraine, he is going to have to go through him.

Trump has accused Biden of trying to stop an investigation into the Ukrainian gas company where his son, Hunter, was a board member.

"Senator, if the overwhelming issue is President Trump must be defeated, do you feel you and other Democrats must be doing more to speak in one voice that Joe Biden’s family is off-limits?" CNN anchor Ana Cabrera asked on Sunday.

"I’ve said time and time again that this is unacceptable, that if you come after Joe Biden you’re going to have to deal with me in this case," Booker said. "These are baseless, unfounded, scurrilous lies plain and simple, trying to undermine the character of one of the statesman of our country, not our party but our country."

"So, yeah, you’ve got a problem with me," he added.

Booker also pointed to Trump's weekend tweets that targeted Sen. Mitt Romney (R-UT), which continued to make fun of his loss against President Barack Obama in 2012, as examples of attacking statesmen.

Mitt, get off the stage, you’ve had your turn (twice)! https://t.co/zz6TA6XoGe — Donald J. Trump (@realDonaldTrump) October 5, 2019

The Democrats are lucky that they don’t have any Mitt Romney types. They may be lousy politicians, with really bad policies (Open Borders, Sanctuary Cities etc.), but they stick together! — Donald J. Trump (@realDonaldTrump) October 6, 2019

Trump's phone call with Ukrainian President Volodymyr Zelensky, pushing him to investigate the Bidens, is at the center of the House's impeachment probe.