WASHINGTON (AFP) - Senior US Senator Chuck Grassley, 87, tested positive for the coronavirus on Tuesday (Nov 17), the latest of some two dozen American lawmakers who have contracted Covid-19 this year as the pandemic surges nationwide.

"I've tested positive for coronavirus. I'll b following my doctors' orders/CDC guidelines & continue to quarantine," tweeted the Iowa Republican, who is the second-oldest senator in the 100-member chamber.

Mr Grassley is also president pro tempore of the US Senate, which makes him third in line to the presidency, after the vice-president and the speaker of the House of Representatives.

He is the second senator to isolate this week, after Florida's Rick Scott entered quarantine for coming into contact with someone who later tested positive for the virus.

Mr Scott has tested negative but remains at home.

Multiple lawmakers tested positive before returning to Washington for a November session, including 87-year-old Republican congressman Don Young of Alaska, the oldest House member.

Congresswoman Cheri Bustos and House Republican Tim Walberg have tested positive in recent days.

By entering quarantine under government health guidelines, Mr Grassley was unable to vote on the floor, which brought his record of 27 years without missing a single Senate roll call to a halt.

Mr Grassley said he is "feeling well and not currently experiencing any symptoms."

Congress has been forced into recess on multiple occasions since outbreaks swelled in the United States in March. Nearly 250,000 Americans have now died from the virus.

A September outbreak was linked to a White House Rose Garden ceremony where President Donald Trump announced Ms Amy Coney Barrett as his Supreme Court nominee.

Mr Trump and First Lady Melania Trump tested positive, as did dozens of others in attendance, including Republican senators Mike Lee and Thom Tillis.

Senator Bill Cassidy, who tested positive for the coronavirus in August, tweeted that he and his wife "are praying for a quick and full recovery for @ChuckGrassley."

With cases skyrocketing to record levels, lawmakers from both parties, including Mr Grassley, have urged Americans to wear masks and social distance whenever possible.

Mask-wearing remains a political issue in Washington, with lawmakers clashing on the Senate floor Monday over whether senators should wear masks when speaking in the chamber.

Mr Grassley is an iron man of sorts, having cast a staggering 8,927 consecutive votes over a record 27 years without missing a single one, until Tuesday.

The last time Mr Grassley missed a vote was July 1993, when he toured flood damage in Iowa with then-president Bill Clinton.

"I'm disappointed I wasn't able to vote today in the Senate, but the health of others is more important than any record," said Mr Grassley.

While he claims the longest period of time without missing a Senate vote, the record for the most consecutive roll call votes is held by Senator William Proxmire, at 10,252.