Democratic leaders and their liberal aides, along with professional agitators, are all intermingled and conspiring together to achieve the same objective — in this case, to spike the confirmation of President Trump’s Supreme Court nominee, Brett Kavanaugh.

Hill Republicans claim Democratic Sen. Dianne Feinstein engineered the kneecapping of Kavanaugh from both inside and outside Congress — and they have a strong case, though Feinstein insists she merely dealt cards she was handed.

For starters, they argue that Feinstein, who is the top Democrat on the Senate committee vetting Kavanaugh, orchestrated an “11th-hour ambush” of the conservative nod by withholding a letter from the committee’s Republican majority alleging sexual misconduct by Kavanaugh until the day the panel was preparing to take a vote to confirm him — almost two months after receiving the letter and well after the vetting and hearing process.

“You chose to sit on the allegations until a politically opportune moment,” a furious Senate Judiciary Committee Chairman Chuck Grassley (R-Iowa) scolded Feinstein in a letter dated Sept. 19.

“I cannot overstate how disappointed I am in this decision,” he added. “It has caused me to have to reopen the hearing.”

Grassley suggested that the last-minute allegations were “deployed strategically for political gain.” Democrats are hoping to delay the hearing until after the Nov. 6 congressional elections to give them a chance to win back enough Senate seats to defeat Kavanaugh. Indeed, Feinstein said, “We should delay this hearing.”

But Republicans point to other skulduggery as well.

This spring, Hillary Clinton’s former campaign press secretary Brian Fallon hired one of Feinstein’s top aides on the Judiciary Committee to help tank Trump’s Supreme Court picks from the outside. Together, he and Feinstein’s aide — former deputy general counsel Paige Herwig — launched a liberal nonprofit group called Demand Justice to lead the left’s attack on GOP nominees.

In early July, after Trump nominated Kavanaugh for the high bench, Fallon stated that their primary goal was to “delay” confirmation hearings for him. Meantime, he outlined plans of attack, including ginning up questions about what Kavanaugh “knew and when he knew it” about allegations of sexual misconduct by a federal judge he once clerked for.

Later that month, a letter alleging Kavanaugh was involved in an “attempted rape” while in high school was hand-delivered to Feinstein’s office.

Curiously, Feinstein did not raise the accusation during confirmation hearings earlier this month. Throughout the hearings, however, Demand Justice dispatched protesters claiming Kavanaugh sought to deny women rights, while running attack ads warning he planned to “overturn Roe [v. Wade] and criminalize abortion.” The ads appeared in Alaska and Maine to try to sway those states’ moderate pro-choice Republican senators to vote against Kavanaugh.

The scare tactics didn’t work. Sens. Lisa Murkowski (R-Alaska) and Susan Collins (R-Maine) sent strong signals they would back Kavanaugh, prompting Demand Justice to concede it might be unable to stop the Senate from confirming him.

Then, just days before the committee planned to vote for Kavanaugh, the letter that was handed to Feinstein was, in turn, leaked to the media and the accuser was identified. Christine “Chrissy” Blasey Ford, a registered Democrat and donor from San Francisco, claimed Kavanaugh tried to pin her down and sexually assault her at a party while the two were in high school. But her details are sketchy. She can’t remember exactly when or where the alleged incident took place, and she concedes she didn’t tell anybody about it at the time, making it hard to corroborate her story.

Kavanaugh, for his part, has categorically denied the allegation both publicly and during a committee staff interview conducted last week “under penalty of felony.” Grassley is trying to negotiate a public hearing to air the charges.

Last month, Blasey Ford took and allegedly passed a polygraph test conducted by a former FBI agent, and hired a law firm headed by major Democratic donors and activists who are working with Demand Justice to smear Kavanaugh as a sexual predator. They’ve created a website, IBelieveChristineBlasey.com , that encourages voters to call their senators and ask that they vote against Kavanaugh. The site maintains that “Brett Kavanaugh is NOT credible in his denial. Kavanaugh’s nomination is on the ropes; he has everything to gain by lying. He has already lied, multiple times, under oath before the Senate. There is no reason to trust his word now.”

Blasey Ford’s lead attorney, Debra Katz, at the same time heads a leftist advocacy group funded by liberal megadonor George Soros, who also is funding Demand Justice, which has raised $5 million to sink Trump’s high court picks. In a new attack ad, the group compares Kavanaugh to “child predator” Judge Roy Moore.

Who paid for Blasey Ford’s polygraph, and who is covering her legal bills? Who leaked her letter to the Washington Post? Katz and Demand Justice did not reply to requests for comment. Nor did Feinstein’s office.

But one thing is for sure: Feinstein and her former aide’s fingerprints are all over the smearing of Kavanaugh — and that’s an ironic shame, given that Feinstein was swept into Congress as a reaction to the then-Democratic Senate’s mishandling of the Anita Hill-Clarence Thomas sex allegations. The San Francisco-based senator has made her own missteps some 25 years later.

Sperry is a best-selling author and a former Hoover Institution media fellow.