A new poll confirmed Sunday that Kamala Harris -- set to name her vice presidential pick imminently -- has drawn level with Donald Trump, transforming a White House race that the Republican had been increasingly confident he was going to win.

As the November 5 election rapidly approaches, Harris has erased the growing lead that Trump was building before President Joe Biden dropped his reelection bid.

According to the CBS News/YouGov poll released Sunday, Harris has a one percent advantage on Trump nationwide -- compared to Trump's previous five point edge on Biden.

In the swing states that decide the Electoral College contest in US elections, Harris and Trump -- who shocked the world with his 2016 presidential victory but was beaten by Biden in 2020 -- are equal.

These are considered good numbers for a Democratic candidate who parachuted into the race only last month, when Biden bowed to mounting concerns over his mental acuity and ability at 81 years old to serve a second term.

But Harris, who is Biden's vice president and the first Black and South Asian woman ever in the role, is in a sprint to define herself to voters before Trump does.

A big moment in that process will be when Harris announces her choice for running mate in a historic bid to become America's first female president. This could happen as early as Sunday or Monday.

Expectations are that Harris will pick a white man to balance the ticket -- and likely a moderate Democrat who would help counterweigh attacks on Harris from Republicans that she is too far to the left.

VP shortlist

The three figures seen as heading the short list -- Minnesota Governor Tim Walz, Pennsylvania Governor Josh Shapiro and Senator Mark Kelly of Arizona -- were all visiting Harris in Washington on Sunday, The Washington Post reported.

"It's her first major decision that she's making as an executive, so it tells you about her thought process," Amy Walter, a polling expert from Cook Political Report newsletter, told CBS News.

The CBS poll, which echoes numerous other surveys indicating rapid gains by Harris, shows that Trump is still favored by voters on the key issue of the economy.

Only 25 percent said they expected to be better off financially if Harris wins, compared to 45 percent who said so about Trump.

However, when it comes to trust in the candidates' temperament, the poll shows voters prefer the former California prosecutor to Trump, a convicted felon who has made a career out of publicly insulting those who oppose him -- including while president.

The issue of cognitive health, which used to bedevil Biden, is now a liability for 78-year-old Trump, the poll found. Only 51 percent of respondents thought Trump is mentally capable for the presidency, compared to 64 percent for Harris.

The Democrats believe that if you "make this referendum on Trump rather than a referendum on the current state of the economy, then we have a real opportunity to win," Cook said.

Trump was riding high politically last month after surviving an assassination attempt at a rally, then using the Republican convention to highlight his image of vigor against the physically frail Biden.

But with Biden's dramatic exit and Harris's fast start, he's scrambling to recalibrate.

At a rally on Saturday in the swing state of Georgia, Trump called Harris a "Marxist" and a "radical left freak," claiming she would cause an "economic crash." On Wednesday, he shocked many when he told an audience of Black journalists that Harris had "turned Black" out of political expediency.

Where Biden often attacked Trump as a threat to democracy, given his unprecedented refusal to accept his loss in 2020, Harris's team has honed a sharper -- more meme-friendly -- line built around branding Trump and his vice presidential pick J.D. Vance "weird."

On Saturday, the Harris campaign said Trump was "scared" to debate her after he turned down a previously scheduled televised debate on ABC, while saying he'd be ready to debate her on Fox News -- a network that has for years given him support.

© Agence France-Presse