Vice President Mike Pence received word that Sen. Kamala Harris had been selected as Joe Biden’s running mate as he headed to an event in Arizona Tuesday -- and said he's looking forward to debating her this October in Utah.

“On the way here I learned that Joe Biden named his running mate,” Pence said to a rally in Mesa, Ariz., followed by boos from the crowd.

“As you all know, Joe Biden and the Democratic Party have been overtaken by the radical left. So given their promises of higher taxes, open borders, socialized medicine, and abortion on demand, it's no surprise that he chose Senator Harris,” Pence said.

“So my message to the Democratic nominee for vice president: Congratulations. I'll see you in Salt Lake City,” Pence told the crowd of Trump supporters.

BIDEN VP FINALISTS PRAISE KAMALA HARRIS

Critics and supporters believe she will be a tough opponent on the debate stage in October.

"She will give Vice President Pence a very, very, very bad evening on that debate because she’s a great debater. She knows what she’s about,” Rev. Al Sharpton said on MSNBC Tuesday. “I think Joe Biden could have chosen someone else, but he couldn’t have chose anyone better."

"She’s tough, she’s thorough, and she’s ready," Sharpton added.

Harris, who has developed a reputation for her “tenacity” and “fighting tooth and nail,” was selected by Biden Tuesday – citing her tough qualities as his reasoning behind his decision.

“Her record of accomplishment — fighting tooth and nail for what’s right — is why I’m choosing her. There is no door Kamala won’t knock on, no stone she’ll leave unturned, if it means making life better -- for the people,” Biden said in his announcement regarding his pick for VP.

“If I were Donald Trump and Mr. Pence, I would be ready for a real battle now,” Sharpton said Tuesday.

HILLARY CLINTON PRAISES KAMALA HARRIS RUNNING MATE PICK

President Trump has already ramped up his aggressive rhetoric and honed in on Harris’ hard prosecutorial style from the debate stage to the Senate floor, referring to her as “nasty” – a word he used to criticize Hillary Clinton in the 2016 presidential race.

"I’ve been watching her for a long time. I was a little surprised," Trump said in a Tuesday briefing, his first public appearance after Biden’s VP candidate was announced. "She was extraordinarily nasty to Judge Kavanaugh.”

“She was nasty to a level that was just a horrible thing, the way she treated now-Justice Kavanaugh, and I won’t forget that soon,” Trump said.

"She was very, very nasty. She was probably nastier than even Pocahontas to Joe Biden," Trump added, referring to Sen. Elizabeth Warren, D-Mass., who has endorsed Biden and voiced her support for Harris as vice president.

But not everyone is convinced that Trump’s notoriously “nasty” behavior will affect Harris’ ability to debate Pence or drive attention on the campaign trail.

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"I don’t think that you could have a tougher opponent," Sharpton added Tuesday. "I know the Trump people are preparing all they can to throw at her, but you cannot have a better person to throw it at — that it will bounce off her like it didn’t mean anything because she’s been in tough fights before.”

Sharpton’s words come after his severe criticism of the candidates throughout the race, saying that “he didn’t see anybody” including Biden or Sen. Bernie Sanders, D-Vt., that could beat Trump after a debate in January.

The vice presidential debate is expected to be held on Oct. 7 in Salt Lake City.