WASHINGTON (Reuters) - A bipartisan group of congressional leaders will receive a briefing on the FBI probe into Russian election meddling, likely in early June, the White House said on Wednesday, following one planned for Thursday to which no Democrats were invited.

The briefing for the leaders from the Senate and House of Representatives, known as the Gang of 8, would take place after the Memorial Day congressional recess, White House spokesman Raj Shah said in a statement.

Two Republican lawmakers, and no Democrats, are expected to attend the Thursday meeting to review classified information relating to U.S. President Donald Trump’s suggestion the FBI might have used an informant to gather information on his 2016 election campaign.

However, Representative Adam Schiff, the top Democrat on the House Intelligence Committee and a member of the Gang of 8, told MSNBC late on Wednesday that it was possible the group might attend Thursday’s briefing.

“It is still not clear to me what is going to happen tomorrow. I was informed by the head of one of our intelligence agencies earlier tonight that a meeting or briefing tomorrow would be a bipartisan briefing at a Gang of 8 level, and that would be it and I expect them to live up to that commitment,” Schiff told MSNBC.

Senate Democratic leader Chuck Schumer has called the plan to review classified information highly inappropriate and said such a meeting must include Democrats as a “check on the disturbing tendency of the president’s allies to distort facts and undermine the investigation and the people conducting it.”

Trump’s closest conservative allies in Congress have been clamoring for access to the classified documents. The lawmakers have accused the FBI and Justice Department of political bias against Trump in favor of his Democratic rival, Hillary Clinton, during his successful presidential campaign.

The Thursday meeting attendees will be Representatives Devin Nunes, chairman of the House of Representatives Intelligence Committee, and Trey Gowdy, chairman of the House Oversight Committee, the White House said on Tuesday.

FBI Director Christopher Wray, Director of National Intelligence Dan Coats and Acting Principal Associate Deputy Attorney General Ed O’Callaghan from the Justice Department are also expected to attend.

On Tuesday, a group of Republican lawmakers called for the appointment of a second special counsel to investigate the probe into Trump’s campaign, Russia and the 2016 U.S. election, as Trump ramped up his own criticism of the Justice Department.

Conservatives have been criticizing the department, the FBI and Special Counsel Robert Mueller’s probe of Russian interference in the election for months. Their rhetoric intensified after Trump started suggesting on Friday that the FBI might have planted or recruited an informant in his presidential campaign for political purposes.

Moscow denies election meddling and Trump denies any collusion between Russian officials and his campaign, calling investigations a political witch hunt.

On Monday, the Justice Department agreed to investigate “any irregularities” in FBI tactics related to Trump’s campaign. The agreement was made during a meeting between Trump, U.S. Deputy Attorney General Rod Rosenstein and Wray.