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President Trump, in his first on-camera remarks about the new Biden-Harris ticket, said he was “a little surprised” that Joe Biden chose Kamala Harris to be his running mate given her “very poor” primary performance -- but said she was his “number one pick” to face off against.

During a White House briefing Tuesday afternoon -- shortly after Biden announced Harris as his VP nominee -- Trump lashed out against the Democratic senator.

The president, referring to her failed 2020 presidential run, claimed he was most surprised by the pick because “she did very very poorly in primaries, she ended up right around two percent.” And he drew attention to her campaign attacks on Biden at the time.

KAMALA HARRIS CHOSEN AS BIDEN'S VP: WHAT TO KNOW 

“She was very disrespectful to Joe Biden. It's hard to pick someone that was that disrespectful,” Trump said referring to a debate moment to Harris’ blitz against Biden in last summer’s primary debates.

On the debate stage in Miami, Harris criticized comments by the former vice president spotlighting his ability to find common ground during the 1970s with segregationist senators with whom he disagreed, and over his opposition decades ago to federally mandated school busing.

“Do you agree today that you were wrong to oppose busing in America?” Harris – who is Black – asked Biden during the debate.

“There was a little girl in California who was a part of the second class to integrate her public schools, and she was bused to school every day,” she said. “And that little girl was me.”

Biden’s poll numbers briefly edged down after the debate – and Harris enjoyed a short-lived surge in the polls. But her campaign faltered later in the year, and Harris ended her White House bid last December.

Days earlier, clues of the decision were dropped when Biden was photographed with talking points in his hand  saying of Harris that he does “not hold grudges” and has “great respect for her.”

BIDEN TAPS KAMALA HARRIS AS RUNNING MATE

Also during the press conference, Trump was asked about Harris' record overseeing 1,900 marijuana convictions in San Francisco when she later claimed to have smoked the substance herself, as reported by Mercury News. 

“She is a person that’s told many many stories that were not true,” Trump replied, before pivoting to her positions on other policies. “She wants to raise taxes, slash funds to our military, she’s against fracking...she's in favor of socialized medicine-- she wants to take health care plans away from 180 million Americans.”

After much anticipation, Joe Biden announced Tuesday that Harris, the first Black woman to serve as a major political party’s VP pick, would be running alongside him.

Biden tweeted on Tuesday, "Back when Kamala was Attorney General, she worked closely with Beau. I watched as they took on the big banks, lifted up working people, and protected women and kids from abuse. I was proud then, and I'm proud now to have her as my partner in this campaign."

Immediately after the decision, the Trump campaign released an attack ad labeling the California senator “phony Kamala Harris.”

While Trump seemed to focus his attacks in Tuesday's briefing characterizing Harris as someone who will fight to raise taxes and slash military funding, others question her record as California's "top cop."

Last year Biden accused Harris of keeping nonviolent prisoners behind bars during her tenure as California attorney general because they were a source of cheap labor for the state.

“What happened? Along came a federal judge and said enough is enough and he freed 1,000 of these people,” Biden said as he argued that Harris was forced by a judge to release the prisoners.

Fellow Democratic presidential candidate Tulsi Gabbard also jumped in to land heavy blows at the time – accusing Harris of keeping “people in prison beyond their sentences to use them as cheap labor for the state of California.”

While the intra-party rifts from 2019 appear to have healed long ago, the attacks from past primary debates could be used as ammunition by Trump’s campaign and allied groups to target Biden and Harris. And it remains unclear whether the progressive flank of the party will embrace her.

But Harris' tough-on-crime could complicate Trump's attempts to differentiate himself as the "law and order" pick for president. He has said a Biden administration would bow to the far-left "defund the police" movement. He has claimed rioters would "destroy our American cities" under Biden.

"The Fake News Media is trying to portray the Portland and Seattle 'protesters' as wonderful, sweet and innocent people just out for a little stroll. Actually, they are sick and deranged Anarchists & Agitators who our great men & women of Law Enforcement easily control, but who... would destroy our American cities, and worse, if Sleepy Joe Biden, the puppet of the Left, ever won," Trump said in a pair of tweets in late July.

Trump continued: "Markets would crash and cities would burn. Our Country would suffer like never before."

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Trump has also previously said that "[n]o one will be SAFE in Joe Biden's America!" in a tweet that claimed the presumptive Democratic nominee wants to abolish police, Immigration Customs and Enforcement (ICE), suburbs and the Second Amendment -- Biden has not said he would abolish any of those things.

Fox News' Alex Pappas, Paul Steinhauser and Tyler Olson contributed to this report.