At a certain level, public-opinion polls on federal criminal investigations seem unimportant. After all, law-enforcement officials are not politicians, and while they serve the public’s interests, they also have a job to do that has little to do with popular will.

That said, I tend to keep an eye on polling related to Special Counsel Robert Mueller’s probe, not because public attitudes should shape the direction of the investigation, but because I’m interested in whether the Republican campaign to undermine public confidence in the probe is working.

Donald Trump, for example, has characterized the investigation itself as “illegal” and “corrupt.” His allies in Congress and conservative media have mounted a spirited campaign against Mueller, the FBI, and the Justice Department, which collectively have become a bete noire for the right.

The American mainstream isn’t buying it.

A clear majority of Americans support special counsel Robert S. Mueller III’s investigation of Russian interference in the 2016 election and alleged collusion with President Trump’s campaign, a new Washington Post-ABC News poll finds. The results show backing for inquiries into Trump’s orbit on several fronts. Nearly 7 in 10 adults say they support Mueller’s focus on possible collusion with Russia. Sixty-four percent say they want the special counsel investigating Trump’s business activities. And a 58 percent majority supports investigating alleged payments by Trump associates to silence women who say they had affairs with him.

Just to clarify, whether Mueller and his investigators have any interest in Trump World’s hush-money scandals is unclear, but the point is there’s a fair mount of public support for examining this and related Trump controversies.

This comes on the heels of a March poll from Pew Research Center showing broad public confidence in Mueller’s efforts.

To be sure, a closer look at the details of the data suggests self-identified Republican voters have largely embraced their party’s message. In the Washington Post/ABC News poll, for example, a majority of GOP voters said they didn’t want Trump investigated for any of the aforementioned reasons.

And for the White House, maybe that’s enough. Perhaps persuading like-minded partisans to buy into the president’s pushback is enough.

But if Trump intended to persuade the American mainstream, it doesn’t appear to have worked.