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The FBI paid visits to Republican congressional candidate Robert Hyde's Connecticut home and business on Thursday, a senior law enforcement official said.

The agent's visits came days after the House Intelligence Committee released texts Hyde sent an associate of Rudy Giuliani, a personal lawyer for President Donald Trump, suggesting that he had Marie Yovanovitch, then the U.S. ambassador to Ukraine, under surveillance.

A spokesperson for the FBI field office in New Haven, Connecticut, declined to comment. Hyde did not immediately respond to a request for comment on Thursday.

One of Hyde's neighbors told NBC News that an FBI agent arrived at Hyde's home before dawn and parked out front in a gray SUV. The neighbor said they believed the FBI agent did not enter Hyde's home and left by 10:30 a.m. Hyde has a "No Trespassing" sign on his property and a sign indicating that security cameras are in operation, the neighbor said.

Hyde said this week that he had been drinking and was not serious when he sent the texts to Giuliani's now-indicted associate Lev Parnas. In an interview with MSNBC's Rachel Maddow on Wednesday, Parnas called Hyde a "weird" character whom he met at Trump International Hotel in Washington, D.C., and said he doubted that Hyde was actually tracking Yovanovitch.

"Well, I don't believe it's true," he said of Hyde's claims. "I think he was either drunk or he was trying to make himself bigger than he was, so I didn't take it seriously."

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Democrats have called for an investigation into Hyde's texted claims. Ukraine announced Thursday that it is investigating the allegations.

Hyde, a onetime landscaper, sent messages to Parnas indicating that he was tracking Yovanovitch's movements in Kyiv before she was recalled as ambassador in May. Giuliani was pushing for Yovanovitch's ouster because she was seen as an impediment to having Ukraine announce an investigation into former Vice President Joe Biden, his son, Hunter Biden, and other Democrats.

"They are moving her tomorrow," Hyde said in a message to Parnas on March 25.

"She's talked to three people. Her phone is off. Computer is off," he said in another text. "She's next to the embassy. Not in the embassy."

House Foreign Affairs Committee Chairman Eliot Engel, D-N.Y., called the text exchanges "profoundly alarming."

"The messages suggest a possible risk to Ambassador Marie Yovanovitch's security in Kyiv before she was recalled from her post last year," Engel said. "These threats occurred at the same time that the two men were also discussing President Trump's efforts, through Rudy Giuliani, to smear the ambassador's reputation."

Yovanovitch's attorney, Lawrence Robbins, called for an investigation into the allegations Tuesday. Connecticut Republican Party Chairman J.R. Romano asked Hyde to end his campaign, saying his "antics" were a distraction.

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Hyde has run into legal trouble in the past, having had his guns taken away in June because of a protection order, The Associated Press reported. In June, police responded to a complaint from a church saying Hyde was attending services and took videos of himself in and around the church to use for political campaign purposes, posting them on social media. The church requested that police ask Hyde not to return.

Hyde, a former Marine, began donating to Trump's presidential campaign and the Republican National Committee in September 2016, sometimes writing multiple checks a day.

The donations appear to have gotten him entry into Trump's orbit. He has tweeted pictures and videos with the president at various events and has posted pictures with the president's adult children and various other Trump associates.