By Devan Cole, CNN

(CNN) -- A number of prominent Republicans have endorsed Joe Biden's presidential bid, handing the former vice president potentially useful support as he looks to win over dissatisfied members of the party.

Among the list of GOP supporters are several figures who spoke during the first night of the Democratic National Convention on Monday, making the case that Biden can usher in a new era of political unity following four years of President Donald Trump.

Here are some of the high-profile Republicans who have endorsed Biden:

Former Ohio Gov. John Kasich

Kasich, who served for eight years as Ohio's governor and was a candidate for the GOP nomination in 2016, has turned into a prominent voice of the party's "Never Trump" movement. Among the Republicans featured at the Democratic convention, he was given the longest amount of speaking time, using the moment to call on fellow Republicans to vote for Biden.

"I'm sure there are Republicans and independents who couldn't imagine crossing over to support a Democrat," he said on Monday. "They fear Joe may turn sharp left and leave them behind. I don't believe that because I know the measure of the man. It's reasonable, faithful, respectful, and, you know, no one pushes Joe around."

Former New Jersey Republican Gov. Christine Todd Whitman

Whitman served as New Jersey's governor before being tapped by President George W. Bush in 2001 to head the Environmental Protection Agency. Speaking briefly during the convention on Monday, she said the election "isn't about a Republican or Democrat. It's about a person: a person decent enough, stable enough, strong enough to get our economy back on track; a person who can work with everyone, Democrats and Republicans, to get things done."

"Donald Trump isn't that person; Joe Biden is," Whitman said.

Former Hewlett Packard CEO Meg Whitman

Whitman unsuccessfully ran for governor as a Republican in California in 2010, but backed Hillary Clinton's presidential bid in 2016.

"I'm a longtime Republican and a longtime CEO," Whitman, who is the current CEO of Quibi, said during the convention. "And let me tell you, Donald Trump has no clue how to run a business, let alone an economy."

Former New York Republican Rep. Susan Molinari

Molinari, who represented New York from 1990 to 1997 before resigning her seat for a career in journalism, also spoke briefly during the convention on Monday, saying Biden is "exactly what this nation needs at this time."

Former senior Trump administration official Miles Taylor

Taylor, who served as chief of staff to Homeland Security Secretary Kirstjen Nielsen, became one of the highest-ranking former Trump administration officials to endorse Biden when he made a surprise announcement Monday afternoon in support of the former vice president.

"Given what I have experienced in the administration, I have to support Joe Biden for president and even though I am not a Democrat, even though I disagree on key issues, I'm confident that Joe Biden will protect the country and I'm confident that he won't make the same mistakes as this President," Taylor said in a video produced by the group Republican Voters Against Trump in which he also made several allegations about Trump's conduct.

Former Secretary of State Colin Powell

Powell, a longtime Republican who served as secretary of state under Bush, told CNN in June that he'll vote for Biden in the 2020 presidential election.

"I certainly cannot in any way support President Trump this year," Powell said, adding that he couldn't bring himself to vote for Trump four years ago either.

Powell endorsed former President Barack Obama in the 2008 election.

The Lincoln Project

The anti-Trump group is led by several high-profile Republicans, including John Weaver, Rick Wilson, Reed Galen and George Conway, the husband of White House counselor Kellyanne Conway.

The group has endorsed Biden and is primarily known for a series of ads that attack Trump on a number of fronts. The President has labeled the group the "Losers Project" and called its founders Republicans in name only.