Washington DC - Kamala Harris is narrowly beating Donald Trump in a national presidential poll released Tuesday, one of the first conducted since President Joe Biden ended his re-election campaign.

Harris holds a two-point lead over Trump, 44% to 42%, according to the Reuters/Ipsos poll. It was conducted in the two days after Biden announced Sunday he was dropping out of the race and endorsing his vice president.

In the previous week's poll, the two were tied at 44%.

Harris, the overwhelming frontrunner for the Democratic nomination who is raking in endorsements and donations as well as pledged delegates, narrowly trails Republican Trump in another survey also released Tuesday.

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Both results are within the polls' margins of error.

The new surveys followed both the Republican National Convention, where Trump formally accepted the party's presidential nomination, and Biden's leaving the race.

The vice president's performance in the polls, bolstered by the excitement among Democratic voters about the shakeup in the race, shows her apparently neutralizing the bounce that a nominee gets in the days after their party's nominating convention.

She has also hit the ground running on the campaign trail, taking aim at Trump in an exuberant Milwaukee rally on Tuesday.

In a PBS News/NPR/Marist poll conducted Monday, Trump edges Harris with 46% to 45% of US registered voters, with 9% undecided.

If third-party candidates or independents are included in the contest, Trump and Harris are tied at 42%, with the others far behind.

The PBS News survey notably found that 87% of all Americans think Biden's decision to drop out was the right move, a view that crossed partisan and generational lines.

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A plurality of respondents – 41% – said Biden's decision increases Democrats' chances of winning in November, compared to 24% who said it decreases the party's odds and 34% who said it makes no difference.

Both surveys come in the aftermath of Trump surviving a shock assassination attempt at a Pennsylvania rally on July 13.

Trump maintains a very narrow advantage of 1.6 percentage points against Harris, according to an average of polls collated by RealClearPolitics.