When President Joe Biden announced on Sunday that he would exit the presidential race, he quickly endorsed Vice President Kamala Harris as his heir apparent to be the Democratic Party's nominee, and while that endorsement carries some weight, it does not make things official.

That has prompted a resurgence of some interest in the failed 2016 Democratic nominee Hillary Clinton and the notion that she, perhaps more so than Harris, would be the best candidate to take on the Republican nominee, former President Donald Trump, according to USA Today.

Clinton, readers may recall, won the 2016 popular vote against Trump by a sizeable margin but fell short where it matters in the Electoral College. Further, a run as Biden's replacement seems "improbable" since she previously swore never to run for higher office again and was quick to also endorse Harris as the party's presumptive nominee.

Clinton the best choice to replace Biden?

In an op-ed for The Hill, U.K. political adviser and commentator Pablo O'Hana made the case for a Hillary Clinton "Round 2" against former President Trump and argued that she was "one of the most qualified people ever to run for the office."

O'Hana cited Clinton's "unparalleled resume and an unmatched depth of experience" gained from her prior service as Secretary of State, U.S. senator, and first lady, and suggested that her "extensive background in domestic and international affairs" was exactly what is needed right now with multiple developing crises at home and abroad.

It was further observed that Clinton would likely have little trouble raising campaign funds or building a winning coalition of Democratic and independent voters, and argued that she was "a seasoned, savvy, and adaptable candidate" who could run on a platform of "stability, restoration, and progress, with the credibility of her lifetime in public service and proven leadership."

Poll showed Clinton beating Trump

O'Hana's op-ed also pointed to an early July poll from Politico which found that while President Biden trailed former President Trump by one point, 42-43%, and VP Harris led Trump by one point, 42-41%, former Sec. Clinton was up over Trump by two points, 43-41%.

That pollster, former Obama campaign adviser Fernand Amandi, also tested out a variety of Democratic tickets, including one that combined both Clinton and Harris still as VP, and found that the Clinton-Harris combo would defeat Trump and his then-unknown running mate 43-40%.

"I’m really surprised by Hillary’s strength," Amandi told Politico. "While some dismiss her as yesterday’s news and a candidate of the past, voters at least in this poll suggest they may be open to a Clinton comeback and that a ticket with Clinton as president and Harris as vice president is even 'stronger together'" -- a reference to Clinton's 2016 campaign slogan.

Meanwhile, nearly all of the other polls that have matched up Harris against Trump, according to both 538 and RealClearPolling, show that while Harris performs marginally better than Biden did against Trump, she is still trailing him by an average of two points.

Clintons endorse Harris as Biden's replacement

However, the hypothesizing about a former Sec. Clinton rematch against former President Trump will almost certainly remain nothing more than an untested theory, as Clinton has given no real indications that she is prepared or has any plans to jump into the presidential race in place of the ailing and elderly President Biden.

In fact, Fox News reported that mere hours had elapsed on Sunday after Biden announced his drop out from the race and endorsement of VP Harris as his successor that both former President Bill Clinton and the former secretary, senator, and first lady issued an endorsement of their own for Harris to replace Biden as the Democratic nominee.

Their joint statement praised Biden's decision to step aside and said, "We are honored to join the President in endorsing Vice President Harris and will do whatever we can to support her."

That statement went on to warn about the potential dangers of another Trump presidency and added, "Now is the time to support Kamala Harris and fight with everything we’ve got to elect her. America’s future depends on it."