An FBI agent involved in the Russia investigation in spring 2017 expressed hesitation about whether he should join up with special counsel Robert Mueller’s probe because “there’s no big there there,” according to emails made public on Tuesday by a Republican senator.

Agent Peter Strzok exchanged messages with FBI lawyer Lisa Page, with whom he was having an affair, on May 19, 2017 — two days after Deputy Attorney General Rod Rosenstein named Mueller to

investigate possible collusion by President Trump’s campaign associates.

Calling the probe “maybe the most important case of our lives,” Strzok was skeptical it would result in revealing any wrongdoing.

“You and I both know the odds are nothing. If I thought it was likely, I’d be there no question. I hesitate in part because of my gut sense and concern there’s no big there there,” Strzok wrote, according to the message released by Sen. Ron Johnson on a Wisconsin radio show.

In the exchange, Page tried to discourage him from joining Mueller’s team.

“You shouldn’t take this on. I promise you, I would tell you if you should,” she wrote.

“Now I need to fix and finish it,” Strzok replied.

Mueller dropped Strzok from the investigation in July 2017 after the Department of Justice uncovered text messages between him and Page that were anti-Trump.

During the WISN broadcast, Johnson called the messages “jaw-dropping” and pressured the FBI to uncover five months of missing text messages between Strzok and Page.

The department told lawmakers last Friday that it was unable to recover messages sent between Dec. 14, 2016, and May 17, 2017, because of a technical glitch involving agents’ mobile phones that didn’t allow them to retain text messages.

Johnson said the messages offer crucial insight into how the FBI handled the Trump investigation.

“Again, texts between two people having an extramarital affair, and they’re completely unguarded in their communication,” he said. “And so we’re getting insight into exactly what’s happening inside the FBI at the highest levels.”