(CNN) The Trump administration will now brief a bipartisan group of lawmakers in addition to two key House Republicans on a confidential intelligence source in the Russia investigation, after initially scheduling a briefing only for the pair of GOP congressmen.

The Justice Department announced Wednesday evening that it will hold back-to-back meetings on Thursday, one for House Intelligence Chairman Devin Nunes and Oversight Chairman Trey Gowdy and another immediately after for the bipartisan "Gang of Eight" and Gowdy.

At the last minute, the top Democrat on the Intelligence committee, Rep. Adam Schiff of California, was invited to the noon briefing with Nunes and Gowdy, House Minority Leader Nancy Pelosi told reporters, a briefing for which no Democrats had been previously invited. Schiff will attend both briefings.

The "Gang of Eight" consists of the top Republican and Democratic members of the House and Senate intelligence committee as well as congressional leaders from both parties. Their briefing will take place at 2 p.m. ET Thursday in the Senate, according to four sources brief on the plans.

House Speaker Paul Ryan told reporters Thursday that, due to an earlier scheduling conflict, he plans to attend the noon meeting with Gowdy and Nunes, and not the "Gang of Eight" meeting later, which the Wisconsin Republican was invited to as House speaker.

The schedule change occurred following sharp criticism from Democrats that the White House was politicizing intelligence by initially offering the briefing only to Republicans. The White House had announced shortly before the bipartisan meeting was scheduled that they were working on holding a briefing for the "Gang of Eight" before the Memorial Day recess. Hours earlier, the White House had said that the briefing for the "Gang of Eight" would happen next month.

The two briefings could be the culmination of the contentious fight over the confidential source, which has sparked unproven accusations from President Donald Trump and other Republicans that the FBI was spying on the Trump campaign. The President's allies in Congress, however, are skeptical Nunes and Gowdy will get the documents they are seeking.

Nunes and Gowdy are scheduled to meet at noon with White House chief of staff John Kelly, Deputy Attorney General Rod Rosenstein, FBI Director Chris Wray and Director of National Intelligence Dan Coats. Then at 2 p.m., the Gang of Eight, plus Gowdy, will meet with the same administration officials.

The DOJ announcement capped a day of furious negotiations over the Thursday meeting for Nunes and Gowdy. Lawmakers were initially told that the Gang of Eight meeting would be held Thursday, but then it was announced that meeting would be held next month after the weeklong congressional recess, according to a congressional source. But Democrats continued to protest, and the same-day meeting was ultimately agreed to.

When the White House had announced earlier this week the GOP meeting would take place, they said Kelly would not take part and that Rosenstein was not the senior DOJ official attending. But the meeting just for Nunes and Gowdy sparked condemnation from Democrats in Congress. Rep. Joaquin Castro, a Democratic member of the House Intelligence Committee, told CNN he confronted Nunes on the floor and told him Democrats wanted to attend the briefing. Castro said Nunes' response was "I'm not going to play that game."

The White House had initially said that the Democrats had not formally requested to take part in the briefing, despite calls from Senate Minority Leader Chuck Schumer for the meeting to be bipartisan.

Following the newly scheduled Thursday meeting for the "Gang of Eight," the New York Democrat released a statement calling for the canceling of the earlier Nunes and Gowdy briefing.

"While it's a good thing that the Gang of Eight will be briefed, the separate meeting with a known partisan whose only intent is to undermine the Mueller investigation makes no sense and should be called off," Schumer said his statement. "What is the point of the separate briefing if not to cause partisan trouble?"

One person familiar with the situation said that Trump told aides Wednesday, including Kelly, that he wanted the meeting to appear above board and nonpartisan, and to make sure Democrats are able to view the intelligence so they can't accuse the White House of playing games.

He has told advisers he doesn't want the accusations of partisanship to overshadow the larger story, which he believes is a conspiracy by law enforcement against him.

He was annoyed the Democrats had been given the opening by not being invited, the person said.

Trump has seized on reports about a confidential source speaking with his campaign advisers in 2016 to accuse the FBI of spying on his campaign, though US officials have told CNN the confidential source was not planted inside the campaign to provide information.

Kelly is expected to go to the Justice Department to lay the groundwork of what the goal is of the meeting and to make sure there is some sort of resolution so that the members are satisfied.

But Republican critics of the Justice Department and Deputy Attorney General Rod Rosenstein remain deeply pessimistic that the Justice Department will divulge anything on Thursday.

Rep. Mark Meadows, a North Carolina Republican and the head of the conservative Freedom Caucus, told reporters he did not expect the Justice Department to provide Nunes and Gowdy with any of the relevant documents Thursday, saying his prediction is based on both "rhetoric and historical fact."

He reiterated that contempt of Congress should still be on the table if Rosenstein doesn't heed to their demands.

A congressional aide said conservative allies of the President -- including Meadows and Ohio Republican Rep. Jim Jordan, both of whom appealed to Trump directly last week for help in Republicans' quest for documents -- remain concerned that they won't ultimately get their hands on documents they sought Trump's help to obtain, citing fears that the summit this week will not involve an actual review of the records. Instead, some members fear the meeting will feature just another round of negotiations over a future document production that may never materialize, the aide said.

Some of Trump's allies have privately feared that the President's call for an investigation into the FBI's conduct -- which Rosenstein granted Sunday when he referred the matter to the Justice Department inspector general -- could ultimately do more harm than good to their months-long efforts. Trump took to Twitter on Sunday to demand the Justice Department investigate the FBI's use of a confidential source -- a step some of his outside advisers had been encouraging him to take.

But some of the lawmakers who had entreated the President for support in their quest for documents were less enthused about Trump's attempt to help them -- in part because the assistance they had asked for was not what he delivered. Some members fear Trump's attempts to help may backfire.

GOP congressional sources said Trump's latest intervention might actually make the Justice Department less inclined to hand over the documents requested by Republicans on the House Intelligence Committee. If the FBI's use of a confidential source becomes the subject of an active investigation, the sources said, Justice Department officials might have even more reason to withhold records from lawmakers than they do already.

One person close to the White House said senior aides have resisted efforts from Trump allies inside and outside Congress to ratchet up the pressure on Justice Department leaders over the FBI's use of a confidential source.

"There's definitely tension," said the person, who has advised the President on how to approach the Mueller investigation.

"Outside friends of the President ... are far more adamant about confrontation than senior staff at the White House," the person said of the more aggressive approach Trump's group of advisers have advocated. "I think senior staff at the White House are still generally of the view that it's better not to escalate."

This story has been updated with additional developments.