Democratic presidential front-runner Joe Biden has quietly expanded his lead over U.S. President Donald Trump among registered voters, even as the rapidly spreading coronavirus has all but sidelined the former vice president's campaign, according to a Reuters/Ipsos opinion poll released on Tuesday.

The poll conducted on Monday and Tuesday of more than 1,100 American adults found that 46 percent of registered voters said they would support Biden if he were running against Trump in the November 3 election, while 40 percent said they would vote for Trump.

That advantage of six percentage points was up from a one-point lead for Biden recorded in a similar poll that ran from March 6 to 9.

The result suggested that Biden had not been hurt politically from his lack of visibility while the Republican president is at the center of a government response to a pandemic that has infected more than 184,000 people in the United States and killed more than 3,700 people.

Biden, who does not currently hold office, has been struggling to stay in the public eye as the coronavirus forced millions of Americans inside their homes. While Trump has held daily televised briefings about the virus, Biden has had to shut down fundraisers and other campaign events, and election officials in many states have postponed their nominating contests.

Still, the poll found that the number of people who approve of Trump in general, and also those who like the way he has handled the U.S. coronavirus response, had changed very little over the past few weeks. About 44 percent said they approved of Trump's overall performance and 48 percent said they liked the way he had responded to the coronavirus outbreak.

That compared with a 70 percent approval rating among respondents for their state governors' handling of the pandemic.