Mr Trump has long dismissed the Special Counsel investigation into Russian interference in the U.S. election - which is also examining possible obstruction of justice by the president - as a politically motivated "witch-hunt".
Schiff said he was speaking for all the Democrats who attended including top Senate Democrat Chuck Schumer, top House Democrat Nancy Pelosi, and top Senate Intelligence Committee Democrat Mark Warner.
The White House confirmed on Wednesday it's planning for a bipartisan group of House and Senate leaders, known as the "Gang of 8", to receive a highly classified intelligence briefing on the FBI's investigation into Russian meddling, reversing plans to exclude Democrats altogether.
A forthcoming report from the Inspector General's office reportedly contains evidence that senior FBI officials used the resources of the federal agency to infiltrate the 2016 Trump presidential campaign. He said he had advised the administration to include Democrats but downplayed Trump's attacks, saying he doesn't worry about any lasting damage to the intelligence agencies. Democrats say that the entire episode - including the president's involvement - is the latest gambit by Nunes and Trump to undermine the special counsel, Robert Mueller and gain information about his inquiry. And Trump took up the cause as the White House tried to combat the threat posed by Mueller's investigation into Russian interference and possible obstruction of justice.
The statement from the White House added: "They also conveyed the President's understanding of the need to protect human intelligence services and the importance of communication between the branches of government".
President Donald Trump responded to James Comey's claim that he and the Republican Party are doing "lasting damage" to the United States with their attacks on the Federal Bureau of Investigation. Trump and his supporters are running with the more dramatic version of events, with the President even making an unprecedented "demand" that the Justice Department investigate the matter.
On Twitter, Trump suggested that the tables had turned on those investigating his campaign for possible collusion with Russian Federation, writing: "What goes around, comes around!" "Large dollars were paid to the Spy, far beyond normal", he said, without citing evidence, before referring to the matter as "one of the biggest political scandals in US history". A White House lawyer, Emmet Flood, and White House Chief of Staff John Kelly showed up for both briefings, although the White House had earlier said it would keep a distance, drawing criticism from Democrats.
"I can't understand why it is inappropriate for White House counsel to be there".
"I hereby demand, and will do so officially tomorrow, that the Department of Justice look into whether or not the FBI/DOJ infiltrated or surveilled the Trump Campaign for Political Purposes - and if any such demands or requests were made by people within the Obama Administration!"
However, the Times reported that Halper also "had contacts" with LTG Mike Flynn, President Trump's first national security adviser going back to 2014. Trump is already claiming that the tables have been turned on the Mueller investigation and the deep state.