Sen. Dianne Feinstein is calling for an investigation of Cambridge Analytica after Republicans ignored her initial inquiries last year.

Sen. Dianne Feinstein — the top Democrat on the Senate Judiciary Committee — is calling on her Republican colleagues to investigate Cambridge Analytica, the scandal-plagued data firm hired by the Trump campaign.

In a letter to Senate Judiciary Chairman Chuck Grassley, Feinstein issued an urgent call for the judiciary committee to schedule hearings and compel witness testimony to address unanswered questions about Cambridge Analytica and its ties to the Trump campaign.

The request comes amid a series of explosive reports detailing Cambridge Analytica’s involvement in potentially illegal activity, including harvesting Facebook data from more than 50 million Americans, and then using it — without their knowledge or consent — to help the Trump campaign.

“[T]hese reports outline serious allegations that foreign actors engaged with a U.S. campaign to create and implement a widespread influence operation that targeted American voters based on the personal information harvested from these accounts,” Feinstein wrote.

“Such activity implicates campaign finance laws and a broader conspiracy to defraud the United States, matters that fall squarely within this Committee’s oversight jurisdiction.”

Feinstein noted that she has already sent letters requesting information from Cambridge Analytica, as well as several Trump campaign officials connected to the firm. Those requests have been ignored, Feinstein said, and the judiciary committee has not taken any action on them.

Since Republicans are the majority in the Senate, it’s up to them to issue subpoenas and schedule hearings.

“As you know, last year I sent a number of letters seeking information from Cambridge Analytica and some of the individuals named in these media reports, including Brad Parscale, Dan Scavino, and Steve Bannon. These requests have been ignored, and the Committee has taken no additional action,” she wrote.

Feinstein’s letter was published just as London’s Channel 4 released an explosive undercover video in which top executives at Cambridge Analytica were caught admitting that they use bribes and sex workers to entrap politicians.

In the video, Cambridge Analytica CEO Alexander Nix also described how the firm uses shadowy front companies, fake ID’s, and sub-contractors to operate secretly in elections across the world.

“These reports raise serious allegations, and the American people need to know how this happened, who knew about it, why steps were not taken sooner to bring it to an end, and what can be done to protect their privacy and the integrity of our elections going forward,” Feinstein added.

The Trump campaign hired Cambridge Analytica in June 2016. Jared Kushner, who was in charge of overseeing then-candidate Trump’s digital operations, brought the data firm into the campaign — a decision that was reportedly cheered on by Steve Bannon, a former vice president of Cambridge Analytica.

The data firm later came under scrutiny amid reports that the CEO had reached out to WikiLeaks founder Julian Assange in an effort to obtain Hillary Clinton’s deleted emails. In another instance, Cambridge Analytica reportedly offered to assist WikiLeaks with the organization of emails that had been hacked from the DNC and Clinton campaign chairman John Podesta.

With the data firm back in the spotlight, Trump has remained silent — giving no indication that he sees a problem with any of these practices or that he would hesitate to hire them again as he makes preparations for his 2020 campaign.

Meanwhile, another Channel 4 exposé is scheduled to be released Tuesday. In that video, Cambridge Analytica executives reportedly state that they won the election for Trump — and describe how they did it.

The truth is coming out. Now, it’s up to Republicans to do something about it.