Washington (AFP) - Donald Trump is not the only Republican in election jeopardy. With the US president's poll numbers tanking 20 days out, his party is furiously scrambling to save red-state Senate seats and maintain control of the chamber.

That could be a tall order, as some party faithful step away from the chaotic and vulnerable president and his handling of the coronavirus pandemic, and Democrats run strong campaigns in critical battlegrounds.

Trump's first debate against Democrat Joe Biden, during which the president refused to condemn white nationalism, and his controversial move to nominate a new Supreme Court justice so close to an election are heaping pressure on down-ballot Republicans in competitive races.

It is such an uphill climb for 2020 Republicans that Senator Lindsey Graham, a high-profile lawmaker chairing the confirmation hearings for Trump nominee Amy Coney Barrett, is in the fight of his political life in South Carolina against a shockingly well-funded rival.

Republicans hold a 53-47 Senate advantage, but trail in four races for Republican-held seats and are bogged down in tossup contests in five other states.

If Democrats gain three seats and the White House in the November 3 election, then the party reclaims the Senate, as a vice president Kamala Harris would break the 50-50 tie. 

"I'm optimistic" of Democrats' chances, Delaware's Senator Chris Coons, a close Biden ally, told AFP late Tuesday.

"I think if the election were held today the Democrats would take control of the Senate."

Statistical analysis website FiveThirtyEight.com puts Democrats' chances of winning back the Senate at 68 out of 100.

Even conservative Senator Ted Cruz, a Trump loyalist, warned on national television that Republicans could face a "bloodbath of Watergate proportions" in November.

Fellow Texan Senator John Cornyn, who is in a tighter-than-expected re-election bid, stopped short of saying embattled Republicans need to jettison Trump to avoid being dragged down by their leader.

"In some of these states he's very popular, so I would think that would be a bad decision," he told AFP.

But Cornyn declined to say whether the president is helping the senator's own cause in Texas. 

"I'm hoping to outperform him in the state," Cornyn said.

Leaning left

The senator most likely to lose his seat, ironically, is a Democrat, Doug Jones in conservative Alabama. Otherwise, Democrats envision gains.

Arizona, Colorado and Maine are three states that have been tilting Democratic for months, and Republicans fear their candidates are being damaged by a president they see as toxic.

Arizona's Senator Martha McSally and Colorado's Cory Gardner were asked at recent debates with their Democratic challengers whether they were proud of their support for Trump. They both dodged.

"I'm proud to be fighting for Arizona every single day," said McSally, a retired fighter pilot who trails former astronaut Mark Kelly by eight points in polls.

Susan Collins of Maine -- a state which, like Colorado, voted for Trump's rival Hillary Clinton in 2016 -- recently broke with the president to oppose his pushing through a Supreme Court nominee so close to an election.

But Collins's Democratic rival, Maine Speaker of the House Sara Gideon, has led in every major public poll in the state this year.

North Carolina is also leaning left, with Republican incumbent Thom Tillis -- who, like Trump, was recently diagnosed with the coronavirus -- losing by an average of 4.3 points in polls to Cal Cunningham.

This is despite a Cunningham sexting scandal that the married retired military officer has acknowledged.

Several tossups

The 2020 Senate map has always favored Democrats, as they are defending 12 seats compared to 23 for Republicans.

But today even states like Iowa, Georgia, South Carolina and Montana are tossups, an extraordinary development for Democrats. 

In a wave election, several more could be in play including Texas, Alaska, Kansas and even McConnell's seat in Kentucky.

In South Carolina, Graham is in double political trouble: his loyalty to Trump and his flip-flop on his own pledge to not move ahead with a Supreme Court nomination during an election year.

"In terms of how this affects the election, time will tell," Graham said Tuesday.

But he dismissed suggestions that Trump and Graham's orchestration of a confirmation process could cost him his Senate seat.

"That's not even a remote consideration for me," he insisted. "Trust me, I know South Carolina. Amy Barrett fits South Carolina."

His rival Jaime Harrison is surging. The Democrat announced he raised $57 million in the third quarter, shattering the previous quarterly record for any US Senate candidate ever.