Senator Mark Udall, D-Colo., has been one of the most vocal critics of U.S. intelligence agencies since before anyone ever heard of Edward Snowden. The senator has blasted the National Security Agency, CIA and FBI all while trying to walk the tightrope between transparency and security. Now that he’s been voted out of office, critics of America's national security policy are wondering what happens next.

In January, after decades in Washington, Udall will give up his Senate seat to Republican challenger Cory Gardner. Gardner has also called on the NSA to change its ways, voting as a member of the House of Representatives for the USA Freedom Act, which would end the bulk collection of American’s phone metadata and end many of the secrets surrounding the Foreign Intelligence Surveillance Court. But as an insider and deal-maker, Gardner is not in the same league as Udall, who served five terms in the House of Representatives before his election to the Senate in 2008.

As a member of the Senate Intelligence Committee, Udall grilled decision-makers in the intelligence world even before Snowden, the former NSA contractor, leaked a trove of classified documents, revealing the size of the surveillance apparatus that was put in place under Presidents Bush and Obama. After the Snowden leak, Udall broke with Democratic Party line to challenge the White House to declassify a CIA torture report, penned a Los Angeles Times editorial with Senators Rand Paul, R-Ky., and Ron Wyden, D-Ore., advocating the end of the NSA’s warrantless surveillance, and called for the resignation of CIA Director John Brennan.

Udall was able to be so vocal even in spite of a reported rift with Sen. Dianne Feinstein, D-Calif., the chair of the Senate Intelligence Committee, because of an unwritten rule that allows senators to carve out their own niche issues. “If an issue is being vocally and energetically addressed by a colleague, senators tend to move on to other issues where that is not true,” Steven Rickard of the Open Society Foundation told the Huffington Post. “There are a lot of Democrats -- and some independents and Republicans -- who care a lot about [intelligence and national security implications].”

Another senator will likely fill the space Udall leaves behind, but the American Civil Liberties Union, for one, doesn’t predict that will be Gardner. As a member of the House, Gardner voted for the USA Freedom Act, but he also voted in 2012 to expand provisions of the Foreign Intelligence Surveillance Act, which gave more power to many of the programs revealed by Snowden.

The most immediate consequence, according to government watchdogs, is likely to be another delay of the release of the classified Senate report on the CIA's “enhanced interrogation” techniques used in the years following the Sept. 11 terrorist attacks. The CIA and Intelligence Committee have sparred over the report’s release for over six months, a battle that only intensified when it was revealed that the CIA had monitored the very computers used by senate staffers to compile the report.

Udall has been particularly outspoken on the issue, saying the American people have a right to know what was done in their name. Trevor Timm, the executive director of the Freedom of the Press Foundation, has turned to Udall to work to end the delay before his tenure ends.