 -- On Capitol Hill, it seems that not a day goes by without another lawmaker -- usually but not always a Democrat -- calling for an investigation, special prosecutor or independent commission to delve into the alleged contacts between the Trump campaign, transition and administration and Russian government officials.

Sources have told ABC News that U.S. authorities were probing communications between the associates and suspected members of the Russian intelligence community ahead of the election, allegations Trump has repeatedly decried as "fake news." An FBI probe into the matter is ongoing.

Below is a look at the existing congressional probes related to the alleged contacts, into Russia, which the intelligence community concluded orchestrated an elaborate campaign to interfere in the 2016 election, as well as the leaks to the media surrounding the stories.

Trump associates' alleged contacts with Russia

Senate Intelligence Committee

Chairman Richard Burr, R-North Carolina, gave the first public details on his panel’s inquiry on Dec. 16, before Trump was sworn in. The probe was prompted by, according to Burr’s statement, “the underpinnings of the intelligence” that prompted the intelligence community to release a statement in October that said it “is confident that the Russian Government directed the recent compromises of e-mails from US persons and institutions, including from US political organizations.” It later revised its mission statement to encompass the revelations from a more detailed January assessment of Russia hacking. Republican leaders have also said they expect the committee to call former national security adviser Gen. Mike Flynn to testify about his contacts with Russian officials. Flynn resigned after misleading Vice President Mike Pence about the contacts. Democrats are criticizing Burr this week over revelations that the White House communicated with Burr and his House counterpart to rebut reports that Trump associates had contacts with Russian officials during the campaign. Over the weekend, Sen. Mark Warner, the top Democrat on the panel, said in a statement, “I have said from the very beginning of this matter that if SSCI cannot properly conduct an independent investigation, I will support empowering whoever can do it right."

House Intelligence Committee

This panel, overseen by Chairman Devin Nunes, never announced a separate investigation of Russia’s actions, but acknowledged in early December that the committee had been “closely monitoring Russia’s belligerence for years.” Nunes also noted that it has been looking into the underlying intelligence that prompted the conclusions in the intelligence community’s January assessment, including Russia’s alleged meddling in the 2016 election. Nunes, a Trump transition adviser, has diverged from the Senate Intelligence Committee in saying he has no plans to investigate Flynn’s conversations with Russian officials, saying in mid-February that “we’re not supposed to be listening to American phone calls.” He has said that he wants the FBI to investigate the leaks that have led to public reports about Trump officials' alleged contacts with suspected Russian officials. Nunes said Monday that his committee is in the early stages of its work, but that his preliminary communication with the Intelligence Community has yielded no evidence of contacts between the Trump campaign and the Russian government, although he admitted that “that doesn’t mean they don’t exist.” But California Rep. Adam Schiff said that the committee has called no witnesses or interviewed the FBI. “We haven't reached a conclusion, nor should we, on issues of collusion because we haven't interviewed a single witness or reviewed a single document,” Schiff said.

Other probes

Senate Armed Services Committee

While this committee, headed by John McCain, is not formally investigating Russia’s interference in the election, as is the Intelligence Committee, McCain has resolved to make cybersecurity, and by extension Russia’s hacking, a big focus. “It’s all part of the larger issue of the cyber threat that we face from Russia, China and other countries. It’s another form of warfare,” McCain said on CBS in December. The committee held a hearing last month, during which Director of National Intelligence James Clapper was asked by Democratic Sen. Claire McCaskill about the president’s statements that appeared to “trash the intelligence community,” like when he questioned their veracity by citing their ultimately incorrect assessment that Saddam Hussein harbored weapons of mass destruction. “There's a difference between skepticism and disparagement,” Clapper said during the Jan. 5 hearing.

Senate Judiciary Subcommittee on Crime and Terrorism

At the beginning of the month, Sens. Lindsey Graham and Sheldon Whitehouse, the chairman and top Democrat on the Judiciary Subcommittee, announced they would be investigating Russian efforts to influence democratic elections in the United States and abroad. “Our goal is simple – to the fullest extent possible we want to shine a light on Russian activities to undermine democracy. While some of our efforts will have to be held behind closed doors due to security concerns, we also hope to have an open discussion before the American people about Russia’s strategies to undermine democracy,” the two said in a statement.

House Oversight/Judiciary Committees

The chairmen of the two panels, Jason Chaffetz and Bob Goodlatte, have urged the Department of Justice Inspector General to investigate the leaks surrounding the Flynn calls with Russian officials, though they also say they are not interested in investigating Flynn himself. “We have serious concerns about the potential inadequate protection of classified information here,” they wrote to the DOJ IG on Feb. 15, two days after Flynn resigned. Chaffetz and his Oversight Ranking Member, Elijah Cummings, are also looking into Flynn’s speaking engagements in Russia in 2014 and 2015 to determine the amount and source of any funding he received to appear, and whether he received payments from foreign sources, which would be in violation of the Emoluments Clause of the Constitution. Chaffetz has also stressed the need to look into the leaks of sensitive information from within the intelligence community.