“Kamala Harris is a California liberal who has already defined herself as a radical Democrat with her support of the Green New Deal, socialized medicine, fracking bans, tax raises and taxpayer-funded abortions,” said Courtney Parella, deputy national press secretary for the Trump campaign.

Some of those attacks will be dismissed as false or exaggerated. But the move to cast Harris as a socialist sympathizer and progressive stalwart comes as the Trump campaign struggles to deploy a similar playbook against Biden, who has mocked the president’s attempts to paint him as a “helpless puppet” of the radical left. Trump’s standing against Biden in polls has barely budged throughout the year despite nickname after nickname, a flurry of vicious tweets and numerous presidential press conferences that he’s used to assail his opponent.

“Do I look to you like a radical socialist with a soft spot for rioters?” Biden asked the crowd on Monday at an event in Pittsburgh, where he distanced himself from calls to ban hydraulic fracking and condemned the rioting, looting and arson occurring in some U.S. cities.

The coming focus on Harris presents some challenges for the Trump camp. The president’s team has repeatedly accused Biden of embracing radical social and economic policies to please left-wing revolutionaries ahead of the November election — a line of attack that could complicate efforts to convince voters he and Harris disagree about the direction of their party and the policies their potential administration should enact.

“You can’t spend the summer telling voters they should be afraid of electing Joe Biden because he’s a socialist and then suddenly say, ‘Harris is the actual socialist and she would be in charge if Biden wins,’” said a former Trump campaign official.

A person involved with the Trump campaign maintained that the campaign’s push in the coming weeks to define Harris would not contradict or undo their messaging on Biden. This person said they will focus on specific issues, like abortion and health care, where they believe Harris has staked out untenable positions for the swing voters Biden is targeting. They say Harris cannot afford to revise these positions if she wishes to remain in good standing with the left flank of the Democratic Party.

For example, after Biden walked back his support for the Hyde Amendment, a decades-old law prohibiting federal funding for abortion, Harris asked him during a Democratic primary debate last year if he regretted his “decision for years to withhold resources to poor women to have access to reproductive health care, including women who were the victims of rape and incest.”

The California senator has also said she supports the Women’s Health Protection Act, federal legislation that would block states from placing restrictions on abortion services — including gestational limitations that prevent women in some states from terminating their pregnancies in the third trimester. Biden has previously backed efforts to outlaw late-term abortion procedures and his campaign has not said whether he would oppose a Republican-led effort to ban abortion after 20 weeks if elected.

“Late-term abortion is a weak spot for Kamala because there’s no way she is going to turn her back on the liberal women in her base,” said an outside adviser to the Trump campaign. “If she even appeared to embrace Biden’s indecisiveness on these issues, she would piss off Planned Parenthood and NARAL beyond words.”

Harris also clashed with Biden over his opposition to a “Medicare for All” health insurance system during the party’s primary last year. She maintained an option for purchasing Medicare plans from private companies in her own proposal as a 2020 candidate last year, declining to go as far as Sen. Bernie Sanders (I-Vt.), whose health care reform legislation she previously co-sponsored in the Senate. Biden has promoted an expansion of the Affordable Care Act and once said he would be open to vetoing Medicare for All legislation if the overall cost placed a financial burden on middle-class Americans.

Harris, whose record as California attorney general includes several lawsuits against oil companies over alleged environmental violations, has also carved out a position to the left of Biden on fracking.

“There is no question I am in favor of banning fracking,” she said during a climate change town hall last September, adding that she would use executive authority to immediately ban fracking on public lands while pressuring Congress to expand the ban to private lands.

It’s not unusual to have two candidates with different policy views on the same ticket. When Vice President Mike Pence signed onto the GOP ticket in 2016, he brought with him a lengthy track record of supporting free trade deals, including the Trans-Pacific Partnership that Trump once likened to “rape.” Pence also called Trump’s proposed Muslim ban, a variation of which he later implemented as president, “offensive and unconstitutional” in a tweet prior to becoming his running mate.

“Paul Ryan’s economic plan was more conservative than [Mitt] Romney’s, and George W. Bush supported a constitutional amendment limiting marriage to a man and a woman in 2004, while [Dick] Cheney spoke supportively of gay marriage,” said Joel Goldstein, an expert on vice presidential history.

“Generally, voters focus on the presidential candidates and their positions. As long as the vice presidential candidate is able to conduct themselves in an able and capable way, their own opinions are not likely to be much of an issue,” Goldstein added.

So far, Harris has emerged as an asset since Biden tapped her as his running mate in August. Her presence on the ticket contributed to a major fundraising boost last month as the Biden campaign and Democratic National Committee raised a record-breaking $364.5 million. And her history-making potential as the first Asian American and Black woman on a major party ticket has helped inject enthusiasm into the party’s base, particularly among female and minority voters, according to recent polls.

In a statement, Harris press secretary Sabrina Singh said Biden’s 2020 rival-turned-running mate “will be doing everything possible to elect him this November.”

“As Senator Harris has said from day one, Joe Biden is the leader our country needs to see us through this public health and economic crisis and build a better future for America. She is Vice President Biden’s partner on this ticket,” said Singh.

The Oakland-born senator already got a powerful first wave of the Trump treatment when the president and his allies questioned her eligibility for office the same week she joined the Democratic ticket — a move that drew widespread condemnation even from some in his own party.

“I just heard it today that she doesn’t meet the requirements and by the way the lawyer that wrote that piece is a very highly qualified, very talented lawyer,” Trump, who was the most prominent figure to promote false “birther” conspiracy theories about President Barack Obama during his first term, said of Harris during a news conference last month.

Though birtherism is unlikely to come up during the Oct. 7 debate between Harris and Vice President Mike Pence, Trump’s running mate is expected to dig into the issues on which Harris and Biden harbor some differences.

A person close to Pence said he will continue to push his view that the Democratic ticket “is a trojan horse for a radical leftist agenda” that aligns with Harris’ political views. This person and others said the vice president will attempt to “box in” Harris to where she must choose to disavow Biden’s positions on certain policy issues or water down her own.

The debate will be an important moment for Pence, who is widely viewed as having presidential aspirations of his own and delivered a strong performance in 2016 against then-Democratic vice presidential nominee Tim Kaine.

“Generally speaking, your focus is on the presidential candidates and their positions in the vice presidential debates — though the vice presidential candidates become a little more important if you’re worried about succession,” Goldstein said, adding that Trump and Biden are the oldest candidates to compete against each other in a presidential contest.

It will also be the first time Pence faces off against a female competitor, let alone a former prosecutor. The Trump campaign insists Harris’ record as a prosecutor is a liability for her and Biden, noting that she once declined to pursue the death penalty against a gang member who killed an on-duty police officer when she was in the midst of a 2004 bid for the office of San Francisco district attorney.

“There have been some very high-profile instances where she refused to seek the death penalty and she’s largely skated by on them until now,” said a senior Trump campaign official.

But Harris’ prosecutorial background could also give her the upper hand when she takes the stage against Pence next month. The California senator deployed some memorable lines during the Democratic primary debates — including during clashes with Biden — where she often stood in sharp contrast to her opponents. Though Trump’s even-keeled vice president is unlikely to be as brash as his boss on the debate stage, Goldstein said Pence must still walk a fine line as he takes on Biden’s running mate.

“When Biden debated [Sarah] Palin in 2008, he was very careful to treat her respectfully and his success in that debate was just that — that he was respectful to her while he stuck to the substance in attacking [John] McCain,” he recalled.