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JD Vance, the Republican senator from Ohio newly tapped as former President Trump's running mate, is hitting the campaign trail on Monday, as Vice President Harris' team scrambles to consolidate support from Democrats a day after President Biden bowed out of the race. 

Vance, who Trump a week ago named as his vice presidential pick on the heels of surviving an assassination attempt in Butler, Pennsylvania, is scheduled to hold a campaign rally in his hometown of Middletown, Ohio, on Monday afternoon. Later Monday evening, Vance is to hold another rally in Radford, Virginia. 

For the first time since Biden announced he would no longer seek re-election, Harris spoke at the White House Monday morning during an event honoring NCAA college athletes. 

"Our president, Joe Biden, wanted to be here today. He is feeling much better and recovering fast, and he looks forward to getting back on the road," Harris said at the start of her remarks. "And I wanted to say a few words about our president. Joe Biden's legacy of accomplishment over the past three years is unmatched in modern history."

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Harris, who recalled first getting to know Biden through his late son, Beau, championed the president's "honesty, his integrity, his commitment to his faith and his family, his big heart and his love, deep love of our country." She said she is a "firsthand witness that every day our president, Joe Biden, fights for the American people. And we are deeply, deeply grateful for his service to our nation."

Vance in Michigan

The Republican vice presidential candidate, Sen. JD Vance, speaks during a campaign rally on July 20, 2024, in Grand Rapids, Michigan. (Anna Moneymaker/Getty Images)

Biden, who has been self-isolating in Rehoboth, Delaware, after testing positive for COVID-19 last week, dropped the bombshell announcement Sunday that he would no longer seek re-election. In a letter shared online, Biden endorsed Harris as the Democratic nominee and said he would focus on his duties for the remainder of his term. He still has not been seen publicly since making the announcement.

Reuters reported that campaign officials have already made hundreds of calls on Harris' behalf insisting that delegates name her the Democrats' presidential nominee during next month's Democratic National Convention in Chicago. 

Trump and Vance at the RNC

Former President Trump and Sen. JD Vance appear on the first day of the Republican National Convention on July 15, 2024, in Milwaukee. (Win McNamee/Getty Images)

Michigan Gov. Gretchen Whitmer, a Democrat once viewed as a potential rival to Biden, said in an X post Monday that she endorses Harris. Another Democrat, Kentucky Gov. Andy Beshear, said during an appearance on MSNBC's "Morning Joe" that he too endorses Harris as president and signaled interest in potentially joining her ticket as vice presidential running mate.

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Harris released a statement Sunday after Biden stepped aside. 

"My intention is to earn and win this nomination," Harris said. "I will do everything in my power to unite the Democratic Party – and unite our nation – to defeat Donald Trump."

Harris speaks at the White House

Vice President Kamala Harris speaks from the South Lawn of the White House, Monday, July 22, 2024, during an event with NCAA college athletes. (AP Photo/Susan Walsh)

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Sources previously told Fox News that the Trump campaign has been preparing for Harris' possible entry into the race for weeks, as increasing numbers of Democratic lawmakers and donors called on Biden to step aside following his stumbling and stalled debate performance in Atlanta last month. 

Fox News' Paul Steinhauser contributed to this report.