Chicago (AFP) - White House hopefuls Kamala Harris and Donald Trump set out Friday on the final 10-week sprint to election day, with the Democrat surging after an electrifying speech accepting the Democratic nomination.

Less than three weeks before the US vice president and the Republican ex-president meet to debate – and only a month before early in-person voting begins – polls show the race is neck and neck.

Harris, a former senator and California prosecutor, leaves Chicago with momentum, having outraised Trump and erased the polling leads he enjoyed before she replaced President Joe Biden on the Democratic ticket last month.

But she is not resting on her laurels.

“On to tomorrow,” she told NBC News after the speech. “That was good – and now we’ve got to move on.”

Dan Kanninen, battleground director of the Harris campaign, cautioned that the race remains “very, very tight.”

A new twist in the already topsy turvy contest could come Friday with the expected announcement by third party candidate Robert F. Kennedy Jr that he is dropping out – and also possibly endorsing Trump.

Kennedy, a conspiracy theorist who has been shunned by much of his famous family, has little support, but even a sliver of extra voters on Trump’s side could turn an election likely to be decided by miniscule margins.

Harris accepted her party’s presidential nomination Thursday on a glitzy final night in Chicago, buoyed by a galaxy of stars, to set the stage for the grueling run-in to November 5.

In just a month, Harris, the first Black woman to top a major party ticket, has raised a record-breaking half a billion dollars, enjoying a political honeymoon that shows little sign of ending.

Her campaign got another potential boost when Federal Reserve chair Jerome Powell said the “time has come” for an interest rate cut – something which will lower mortgage costs and other inflationary pressures for voters.

- Kennedy withdrawal -

Potential headwinds for Harris include internal party tensions over US policy on the Israel-Hamas war and fallout from Kennedy dropping out.

The controversial scion of America’s revered Kennedy clan is planning an announcement in Arizona, while Trump is also campaigning in the state and promising to showcase a “special guest.”

Kennedy’s running-mate, Nicole Shanahan, claimed on X that Democrats were “flooding” her with “frantic calls, texts and emails” and were “terrified of the idea of our movement joining forces with Donald Trump.”

But analysts are mixed on the effect a Kennedy exit would have.

Democratic heavy hitters, from Michelle Obama and Bill Clinton to vice presidential nominee Tim Walz, have warned that the party could still lose to Trump’s Republicans if complacency creeps in.

“If we see a bad poll – and we will – we’ve got to put down that phone and do something,” the former first lady told the party faithful in Chicago.

Walz, a former high school football coach, used a sporting analogy, saying that Democrats were “down a field goal, but we’re on offense and we’ve got the ball.”

- Reaching for the center -

Trump, 78, has been mobilizing his right-wing base with apocalyptic warnings about migrant criminals and painting a dark picture of a country in “decline” that only he can save.

Harris and her Democrats have been reaching toward the center.

Party strategists spent the week in Chicago showcasing a parade of anti-Trump Republicans, including ex-cabinet officials, a small-town mayor and a former statewide office holder.

“If you vote for Kamala Harris in 2024, you’re not a Democrat, you’re a patriot,” former Georgia lieutenant governor Geoff Duncan said.

While they previously characterized Trump as a demagogue, Democrats have instead begun making fun of the Republican nominee in a manner designed to belittle him and dent his aura of invincibility.

Harris, 59, called him an “unserious” person.