No profiles in courage among this bunch.

Six on-the-fence senators – three vulnerable Democrats and three moderate Republicans – are eyeing the polls and hoping for an assist from the FBI as the fate of Supreme Court nominee Brett Kavanaugh rests in their hands.

“This isn’t an easy decision. And honestly, I don’t think it should be easy for anyone,” Heidi Heitkamp (D-North Dakota) said Friday.

She is one of three Democratic senators running for re-election in states that President Trump won resoundingly in 2016. Sens. Joe Manchin of West Virginia and Joe Donnelly of Indiana are in the same boat.

On the Republican side, Susan Collins of Maine and Lisa Murkowski of Alaska are being squeezed by liberal activists on one side and their own party leadership on the other. Meanwhile, Jeff Flake of Arizona is reserving judgment until the FBI investigation he insisted on is complete.

The Senate agreed to delay its final vote on Kavanaugh for up to a week so the FBI can probe last-minute sexual-assault allegations against him. The development gives the ditherers a short respite to rework their political calculus.

The GOP holds a slender 51-49 majority in the Senate – so the Republican leadership can afford only one defection.

In that case, Vice President Mike Pence would break the 50-50 tie to elevate Kavanaugh to the nation’s highest court.

“I support this sensible agreement,” Collins tweeted Friday in reaction to the Judiciary Committee’s statement announcing the FBI’s reopened investigation. But she gave no indication of how she will vote.

Murkowski has also maintained a stony silence about her intentions. On Friday, she tweeted concerns about “the process” and posted, “allowing the FBI up to one week to supplement its background investigation is appropriate.”

Collins and Murkowski’s seats are safe – for now. Neither faces re-election this November. But the blowback for defying the party leadership in such a high-profile vote could be severe.

As two of the Senate’s least conservative Republicans, neither is comfortable voting for Kavanaugh, who is expected to tilt the Court’s balance in a decidedly rightward direction. If the FBI investigation lends any credence to the judge’s accusers, observers expect them to seize the chance to vote against him.

At the same time, they are wary of the Trump Administration’s next move, should the Kavanaugh nomination go down to defeat.

The president’s list of potential Supreme Court nominees includes several thought to be even more hardline than Kavanaugh – including Judge Amy Coney Barrett and Sen. Mike Lee (R-Utah) – who would be difficult to oppose if Kavanaugh gets the boot.

Flake is retiring from the Senate in January. While he voted Friday to send Kavanaugh’s nomination out of the Judiciary Committee and to the Senate floor, the senator said he wouldn’t ultimately confirm the nominee unless the FBI investigated sexual assault allegations against the judge.

“I’m a conservative. He’s a conservative. I plan to support him unless they turn up something — and they might,” Flake told The Atlantic on Saturday.

The comments followed emotional testimony Thursday from Christine Blasey Ford, who accused Kavanaugh of trying to rape her when they were teenagers at a party. The judge passionately denied the allegation.

If two of the three up-in-the-air Republicans stick with the party, Kavanaugh wins the seat – potentially freeing the red-state Democrats to cross the aisle.

Heitkamp, Donnelly and Manchin all joined Republicans to confirm Associate Justice Neil Gorsuch in 2017, acknowledging the fact that the Supreme Court was a top issue driving Trump voters in the presidential election.

A recent poll showed Heitkamp trailing her Republican challenger by 4 points, making her vote on Kavanaugh a potential make-or-break call.

Donnelly is also underwater in Indiana. A poll taken two weeks ago showed his opponent with a 2-point lead.

He announced his intention to cast a “no” vote on Kavanaugh’s confirmation Friday morning – but later appeared to backtrack.

“As it is right now, without all this information, I don’t know how I vote yes without having what I need,” Donnelly told Indiana reporters late Friday, speaking with relief of the reopened investigation.

Manchin, who huddled with undecided Republicans on Friday, has been tight-lipped about his intentions.

Polls show him with a 9-point lead in ruby-red West Virginia – but he could lose supporters if he turns against Trump’s Supreme Court nominee.

A poll released Friday, taken after Thursday’s explosive hearing, pegged support for Kavanaugh at 58 percent among West Virginia voters – and found that fully a third would consider Manchin’s Supreme Court decision when they head to the ballot box.

The survey was sponsored by the conservative Judicial Crisis Network.

The FBI has quickly leaped back into its investigation. It planned to interview two of the judge’s accusers – former Yale classmate Deborah Ramirez and Ford – the Wall Street Journal reported on Saturday.

Under Trump’s order, the probe must be completed by week’s end.

The investigation is limited to “current credible allegations,” according to the Senate Judiciary Committee.

It does not include the lurid charges leveled by Julie Swetnick, the Maryland woman represented by Stormy Daniels’ attorney Michael Avenatti, the Journal reported.

Swetnick claims that a teenaged Kavanaugh orchestrated gang rapes at house parties that she attended when he was in high school and she was a college student.

Police in Montgomery County, Maryland, where Swetnick and Ford allege incidents of sexual assault occurred, said that neither woman has filed a police report.

The statute of limitations on Ford’s allegation apparently expired more than three decades ago. At the time, sexual assault charges had to be filed within a year of their occurrence.