Donald Trump’s political team has been preparing for weeks to take on Vice President Kamala Harris. On Sunday, they came a step closer after President Joe Biden announced he was dropping out of the 2024 race.

“We’re very excited about the fact that he endorsed Kamala,” said Richard Grenell, a former U.S. ambassador to Germany and Trump’s acting director of national intelligence. “As we know, she was never vetted in California. … Kamala Harris is a product of this whole system. She’s very left-wing, unvetted, untested.”

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There’s no guarantee Harris will replace Biden as the Democratic nominee, but in the hours after Biden announced he was dropping out of the race, Biden and several key Democrats, including potential rivals, threw their support behind her candidacy, making her even more popular than she already was.

It’s what Trump’s team and Republicans more broadly expected. And they’re ready for it.

Last week’s Republican National Convention in Milwaukee was filled with attacks on Harris, while Trump’s acceptance speech was written without direct mention of Biden; he improvised only one mention of the current president. During his 2020 acceptance speech, Biden’s name appeared more than 40 times.

“Joe Biden is by far the worst president in the history of the United States,” Trump said in a brief interview with NBC News on Sunday, adding: “We will fix what he did. He should never have been there in the first place.”

Harris, a former senator from California, has said she has yet to “earn and win” the Democratic nomination, but she is currently the only declared candidate and is expected to have a significant lead in the process.

“I think we all knew it was going to happen,” said another Trump adviser.

“It’s better that it happens sooner rather than later so we know who we’re up against,” the person said. “But I think it’s going to be Harris. I can’t imagine they would deny an African-American woman who’s almost a heartbeat away the opportunity.”

In the weeks following Biden’s disastrous debate performance in late June, Republicans began refining a messaging strategy that emphasized Harris, with the idea that she would ultimately emerge as the Democratic nominee.

“Donald Trump will beat any Democrat who can get out of whatever backroom deals are being made at the DNC,” said Tim Murtaugh, a top adviser to Trump’s 2020 campaign. “They all have to answer for the failures of the Biden administration and the damage that’s been done to this country, and they all helped lie to the country about Biden’s cognitive decline.”

Early signs point to a three-pronged attack.

Republicans will focus in particular on the idea that Harris met Biden regularly behind the scenes and engaged in what they call a cover-up, shielding the public from the president’s deteriorating condition.

“I think they need to make it clear that Kamala Harris was the primary complicit in covering up President Biden’s mental decline,” Tricia McLaughlin, a Republican strategist and chief adviser to businessman Vivek Ramaswamy’s 2024 campaign, said of how the Trump campaign will continue to attack Harris going forward.

They will also highlight how Biden, early in his term, put Harris in charge of addressing the “root causes” of the wave of migrants moving north from places like Honduras, El Salvador and Guatemala. That responsibility led Republicans to dub her the “border czar” — a term that has been used with increasing frequency in recent weeks as the GOP has looked to Harris to replace Biden. The term was used in at least seven speeches during the Republican National Convention, and the RNC quickly ran an ad amplifying the political moniker.

“We’re not talking about Barack Obama or even Hillary Clinton,” said Zack Roday, a Republican strategist. “Kamala Harris is, at best, a completely unproven national politician. She is responsible for every failure of Biden and the cover-up surrounding his downfall. Her candidacy is built on a foundation of failure and lies.”

David Bossie, the Republican representative from Maryland and an adviser to Trump, stressed that Trump and Republicans see Biden’s declining age and mental acuity as a cover-up.

“A lot of Democrats and the White House press owe America an apology,” he said. “This has been a cover-up for years and Kamala Harris is the boss.”

The third proposition relies on a different claim, namely that senior Democrats pushed Biden out of the race, thereby trampling on the votes of primary voters who had made it clear that Biden was their preferred candidate. While this approach may seem sympathetic to Biden on some level, it signals a second front in the messaging war. Republicans see it as a potentially neutralizing attack by Democrats who often accuse them of being dangerous to democracy.

“This move demonstrates their elitist mentality and their complete and utter disregard for the voice and will of the American people during the primary process,” Alabama GOP Chairman John Wahl said in an emailed statement. “Democratic voters chose Joe Biden as their nominee, and this outrageous manipulation of the electoral process is disrespectful to the American people and the democratic process.”

The pro-Trump super PAC MAGA, Inc. is also expected to quickly update ads already running in Pennsylvania, Georgia and Nevada with a message focusing on the fact that “Harris was involved in the cover-up,” according to a source familiar with the decision.

“Kamala Harris is less successful than Joe Biden — aside from his failures that cripple her candidacy — and less likable than Hillary Clinton,” MAGA Inc. CEO Taylor Budowich wrote in a text message. “As Democrats navigate this new chaos of their own creation, MAGA Inc. will expose its cover-up and failures that have left our nation suffering.”

Bossie said there is also little difference between Harris and Biden’s positions on key issues like the economy and immigration, with most polls suggesting an effort will be made to tie her to administration policies that are generally unpopular.

“The Biden-Harris administration is the worst in American history,” he said. “Their policies have created a carnage on the southern border, chaos in the economy, and an inflation monster. They have the worst record, and you can’t just put lipstick on a pig.”

Jason Miller, a senior adviser to Trump, told NBC News that the campaign is ready for any scenario Democrats imagine.

“We’ve done the polls, we’ve done the research, we’ve cut the ads. We’re ready. This campaign is ready for anything the Democrats throw at us,” he said. “And what’s really striking about the Harris Biden administration is that Kamala Harris is taking on all the failures of the last three and a half years.”

Miller also said they were prepared for “anyone else,” but his answers were generally focused on Harris.

Biden’s historic exit from the race is just one of the many highs and lows that have marked the 2024 race so far.

For much of the spring and early summer, Biden was seen as the slight favorite, and had what most saw as an easy money advantage going into the race. But after Trump was convicted of 34 felonies related to falsifying corporate records, his political base saw it as an unfair weaponization of the justice system and a flood of campaign contributions came in, beginning to change the narrative of the race.

Democrats have tried to emphasize Trump’s conviction and the fact that it disqualifies him from running for president by either major party. But the issue has not scared off GOP voters, but rather brought them closer together.

Then came Biden’s poor debate performance, which gave Trump and Republicans more momentum. And most recently, there was the July 13 rally in Pennsylvania, where a would-be assassin narrowly missed Trump’s life. The assassination attempt further energized Trump’s supporters ahead of the Republican National Convention.

Now that Biden is leaving office — something many in the party had hoped for — some of those dynamics could now come into play for Democrats.

According to ActBlue, an online fundraising platform that raises money for Democrats, Democrats raised $27.5 million from small donors in the first five hours after Biden’s announcement.

“Rank supporters are energized and excited to support her as the Democratic candidate,” the organization posted on social media.

Justin Day, a top fundraiser for the Democratic Party in Florida who is raising money this election for the Democratic Governors Association, among other organizations, thinks the change at the top of the list will help some Democratic donors be less sidelined.

“I’ve already heard from a number of donors who didn’t participate this cycle who have reached out to me saying they’re all in, regardless of who the nominee ends up being,” said Day, who served as Florida finance chairman for both Hillary Clinton and Barack Obama’s presidential campaigns. “The focus has shifted back to defeating Trump.”

Harris is performing similarly to Biden in most public polls against Trump. In the most recent NBC News poll, Biden and Harris both trail Trump by 2 points, which is within the margin of error.

But there is some hope among Democrats that Biden’s retirement will rid Democrats of the problem of a candidate perceived as too old. Trump is now the oldest major-party presidential nominee in history and the first former president to be convicted of a crime.

“You know, he’s got crimes, he’s got all the liabilities that are still there,” Democratic Rep. Mark Pocan, D-Wis., told NBC News. “We now have someone with energy, with a connection to my state, someone who can talk about the accomplishments that she’s accomplished.”

Peter Navarro, a senior adviser in Trump’s White House, said Biden’s removal would bolster the Trump campaign’s efforts to sway the election around politics, particularly immigration, the economy and education. But he acknowledged that Democrats could already see an advantage by distancing themselves from Biden.

“This was a given and well understood within the Trump campaign weeks ago, and we knew they were going to do this,” said Navarro, who was released from federal prison days ago after being convicted of contempt of Congress in connection with the Jan. 6 investigation.

“I don’t think anything changes with this,” he added. “There may be a little bump just because Biden is so flat.”

However, Rep. Jim Banks (R-Ind.), a Trump-backed candidate for Senate in the state, didn’t think the changing of the guard within the Democratic Party would make much of a difference.

Biden is ending his campaign, Banks said, “which means (Trump) wins by an even larger margin.”