Washington DC - US Vice President Kamala Harris admitted Wednesday she was "scared as heck" that Donald Trump would return to the White House in the November election and urged Democrats to "fight back."

Her comments came after Trump stormed to victory on Monday in the Iowa caucuses, the first step in the Republican nomination race to challenge President Joe Biden later this year.

"I am scared as heck, which is why I'm traveling our country... we should all be scared," she told ABC's The View, while adding: "We don't run away from something when we're scared, we fight back against it."

Harris was responding to a question about reports former president Barack Obama was concerned with the Biden campaign, and to comments by ex-first lady Michelle Obama saying she was "terrified" of a second Trump term.

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Biden has stepped up direct attacks on Trump recently, warning that the twice-impeached former president – who faces 91 criminal indictments – poses a threat to US democracy.

The president's reelection campaign has been giving Harris an increasingly prominent role as it seeks to mobilize Black, female, and young voters for this year's crucial election – even as it alienates many of them through its staunch support of Israel's war on Gaza.

Harris herself suffers from low approval ratings and is a repeated target for Republican attacks saying she's unqualified to take over as president if anything happened to the 81-year-old Biden.

Next week, she will embark on a nationwide tour to promote reproductive freedoms as Democrats seek to make abortion rights a key issue in the 2024 race.