Sen. Rand Paul (R-Ky.) speaks during a hearing before Senate Foreign Relations Committee on July 25 on Capitol Hill in Washington, D.C. (Alex Wong/Getty Images)

Sen. Rand Paul is planning to start a trip to Russia on Monday, a venture aimed at “supporting President Donald Trump engaging around the world,” according to a spokesman.

Paul (R-Ky.) has emerged in recent weeks as a fierce proponent of Trump’s dealings with Russia and its president, Vladi­mir Putin, making him a unique voice in Congress at a time when Republicans and Democrats have been chiding or excoriating the president for not taking a harder line against the Kremlin.

Paul went so far last month as to label the president’s critics as “unhinged” and “crazy” for suggesting that Trump had erred by holding a one-on-one summit with Putin in Helsinki, in which he suggested that he might take the Russian leader’s denials of election interference over the conclusions of his own intelligence community.

He suggested that those criticizing Trump’s efforts at diplomacy with Russia — whose number include House Speaker Paul D. Ryan (R-Wis.) and war hero Sen. John McCain (R-Ariz.) — are simply “people who hate the president.”

In the weeks since announcing his trip, Paul also objected to an effort from Sen. Bernie Sanders (I-Vt.) to affirm the intelligence community’s conclusions about Russian interference, calling the resolution a sign that “Trump derangement syndrome has officially come to the Senate” and an affront to diplomacy.

On Wednesday, top national security officials made a rare appearance in a White House news conference to warn that Russia continues to target U.S. elections, posing an ongoing threat in advance of the 2018 midterms.

Paul is expected to hold meetings with an unspecified list of Russian officials. A spokesman for Paul also did not respond when asked how long Paul expects to be in the country.

His visit comes just a few weeks after a delegation of eight Republican lawmakers visited Moscow for meetings with the Russian parliament, as well as Russian foreign minister Sergei Lavrov. They were not granted an audience with Putin.

Those lawmakers faced scorn at home for making the trip over the July 4 recess, and ridicule in the Russian media for promising to talk tough but adopting a seemingly more conciliatory stance once in Russia. Lawmakers pushed back against that impression, arguing that they had delivered tough messages to the Russians, particularly concerning election interference, during their meetings.

The delegation, which was made up of Sens. Richard C. Shelby (R-Ala.), Steve Daines (R-S.C.), John Hoeven (R-N.D.), Ron Johnson (R-Wis.), John Neely Kennedy (R-La.), Jerry Moran (R-Kan.) and John Thune (R-S.D.), and Rep. Kay Granger (R-Tex.), was the first such congressional delegation to travel to Russia in three years, according to the participants.

No other members of Congress have announced plans to travel with Paul.