Vice President Kamala Harris, who is now frontrunner for the Democratic presidential nomination, has a good chance of making "this a very close race" against former President Donald Trump, former Gov. Chris Christie said Monday.

"Eight years ago, [Trump] ran against a woman for president. When he did, Hillary Clinton was a more known quantity and, quite frankly, was disliked by a lot of voters," Christie said on ABC News' "Good Morning America" on Monday. "Kamala Harris is not personally disliked."

He added, "There's a question of respect and whether they respect her or not. And that's going to be in her control now. If she performs well she'll make this a very close race."

A decision about Harris' vice presidential running mate will be closely watched, he said, adding that choosing Gov. Josh Shapiro could deliver his home state of Pennsylvania, which "allows them to play in Michigan, Wisconsin, Arizona."

Christie, who faced Donald Trump as a presidential candidate in the 2016 race, has become an outspoken critic of the former president. He had previously said a second Trump term would amount to a "vendetta presidency."

"And I think he will use the levers of government to punish the people who he believes have been disloyal to him or to his approach," Christie told ABC News earlier this year.

Christie was joined Monday on "GMA" by Democratic strategist and former DNC Chair Donna Brazile, who vowed the convention would have a "transparent process."

"We're going to continue to get the endorsements and, hopefully, at some point today or tomorrow the vice president will have enough delegates to secure the nomination," she said.

-ABC News' Kevin Shalvey

In the hours since President Joe Biden endorsed Vice President Kamala Harris on Sunday afternoon, she has collected $49.6 million in grassroots donations, the campaign said.

-ABC News’ Rick Klein

More than 45,000 people gathered late Sunday on a Zoom call organized by Win With Black Women to support Vice President Kamala Harris' campaign.

The group said it raised over $1,500,000 in about 100 minutes.

The call was led by the group's founder, Jotaka Eaddy, and included lawyer Star Jones, Rep. Joyce Beatty and Shavon Arline-Bradley, the president and chief executive of National Council of Negro Women. Guests such as actor Jenifer Lewis and Alpha Kappa Alpha Sorority President Danette Anthony Reed chimed in with words of encouragement and wisdom.

Even after 1 a.m. on Monday, people continued trying to join the call, and donations kept pouring in. Zoom lifted the capacity limit to allow more people to join the call.

"Don't you ever lose faith in Black women," said Dr. Johnnetta B. Cole, a former president of Spelman College.

-ABC News' Katrina J. Davis

Vice President Kamala Harris on Sunday morning had multiple phone conversations with President Joe Biden before he announced that he would not be seeking reelection and would instead endorse her, according to a source familiar with her schedule.

Surrounded by family and staff at the vice president's residence, Harris spent more than 10 hours placing calls to over 100 party leaders, members of Congress, governors, labor leaders and leaders of advocacy and civil rights organizations. On each of those calls, Harris made clear that she was extremely grateful for the president's endorsement but plans to work hard to earn the Democratic nomination in her own right, the source said.

One of the calls was to her pastor, Amos Brown III, who, along with his wife, prayed over her, according to the source.

The vice president wore a hooded Howard University sweatshirt, workout sweats and sneakers throughout the day. Amid the many calls, she took time to arrange both lunch and dinner for the assembled aides. The menu was salad and sandwiches for lunch and pizza and salad for dinner. Harris' pizza came with anchovies, her go-to topping, the source said.

-ABC News’ Gabriella Abdul-Hakim, Fritz Farrow and Will McDuffie