The Obama era hasn’t been a period of progress for black Capitol Hill staffers, and aides say a “diversity drain” of many senior African Americans to the private sector and the White House in recent years is partly to blame.

“I started on the Hill 10 years ago, and I don't see a significant difference in the number” of black congressional staffers, John Jones, the chief of staff to Rep. Emanuel Cleaver, told The Daily Beast. “[Progress] definitely has stalled… From my own eyes, and what I interact with and what I see, I haven't seen much of a change."

Jones’ view was echoed by other long-serving African-American staffers. They add that the election of the nation’s first black president has come with unintended consequences for Capitol Hill diversity, including a perceived complacency in hiring minorities.

“There’s a challenge with having an African-American president… too many people are under the impression that we live in a post-racial society. Though that goal is within reach, we have not reached that goal,” Jones said. “There’s not a desire to put that emphasis in terms of hiring and diversity.”

Companies, lobbying shops and government relations groups saw it differently. After President Obama was elected, top African-American staffers said, private sector groups interested in influencing the new administration decided to consider more minority candidates. This compounded the diversity problem on Capitol Hill.

“A lot of companies, lobbying shops, government relations groups saw the need to further diversify their talent in the Obama era, so I think that the Hill had a bit of a diversity freeze… A large number of African Americans left the Hill to go the private sector and the Obama administration,” said one former Senate staffer, who characterized the phenomenon as a “diversity drain.”

What little data there is on African Americans on the Hill suggests a long-running problem that preceded Obama’s tenure—and will in all likelihood outlast it.

“Regardless of the president, and what color the president is, [the lack of Capitol Hill diversity] was a problem before and it will be a problem after,” said Rodell Mollineau, a former staffer to Senate Majority Leader Harry Reid and now chairman of Democratic GAIN, an association of progressive political professionals. “There weren’t a lot of people of color to begin with.”

When the National Journal profiled 288 top Capitol Hill aides in 2011, they found that just 7 percent of them identified as minorities.

In 2006, Democrats circulated a survey which showed only 6 percent of Senate employees were people of color, and a 2007 Politico report suggested just 125 Senate staffers—which amounts to just 2 to 3 percent of total aides—were black.

The Brooke-Revels Society, a group of African-American Senate staffers and interns, had a membership of just 75 at last count, the organization told the Beast.

For comparison, the Sunlight Foundation found that the number of Senate staffers has remained stable since the late 1970s, at around 5,100 staff members.

There are no formal figures reflecting the number of African-American staffers on Capitol Hill, and leaders of the Senate Black Legislative Staff Caucus did not respond to a request for comment.

The Daily Beast asked spokespeople for House Speaker John Boehner, House Minority Leader Nancy Pelosi, Senate Majority Leader Harry Reid and Senate Minority Leader Mitch McConnell what percentage of their staffs were minorities.

Only Pelosi’s office originally responded with a figure: 33 percent of their staff consists of people of color, including senior staff positions like chief of staff, member services director and national security advisor.

“Our office’s Member Services team works closely with Member offices, freshmen in particular, to encourage diversity in hiring among staff as well. Our office regularly provides resumes of qualified and diverse candidates to offices,” Pelosi spokesman Drew Hammill said.

After this story published, Reid's office told The Daily Beast that 30 percent of their staff consists of people of color.

Reid’s office also highlighted their office’s Senate Democratic Diversity Initiative, which distributes resumes to other offices to increase the visibility of minority candidates. Reid spokesman Adam Jentleson said that staff diversity in Senate Democratic offices has increased since the initiative was started seven years ago, but declined to provide statistics “since they go beyond our office.”

“Before Sen. Reid started this work, it wasn’t a very diverse place. He started from scratch, almost, and worked up from there,” said former Reid staffer Mollineau. “Sen. Reid can’t do this by himself. He can’t force people to be more diverse. I would challenge each Senate office to take a look at their offices and see whether or not they can do better.”

The top congressional Republican leaders were brief in their responses, and didn’t provide details. “The Speaker believes it is everyone's responsibility to ensure that we have the highest-quality workforce in the House,” Boehner spokesman Michael Steel said. McConnell spokesman Don Stewart commented that their “office is an equal employment opportunity employer.”

For the time being, African Americans on both sides of the aisle talk about how lonely it can become on the Hill—and how the lack of diversity can have political consequences.

“There have been plenty of times when I’ve been in meetings as the only African American there. It’s something you’re aware of, and it’s not a positive thing, to know that it’s not the only black voice in a row,” one GOP Capitol Hill staffer said. “If you get here, and you’re a person of color, there’s no one here to mentor you... It’s kind of something you have to get used to on your own.”

Added the GOP staffer, “There are moments when you’ll hear a politician speaking, and you wonder if he had an African-American staffer, that he’d understand why that wasn’t a wise thing to say.”

The lack of mentors has been a long-standing problem—when Jones, now a chief of staff, first arrived on Capitol Hill a decade ago, he faced the same issue.

“I did not have any African-American male staffers who were older than me that I saw could serve as a mentor. There wasn’t a lot to choose from. There was a very limited number,” Jones told the Beast.

Numerous staffers insist that the only way forward is to institute policies that would encourage greater diversity. Since at least 2007, some Democrats have called for the implementation of the “Rooney rule” on Capitol Hill. Inspired by an NFL regulation, the rule would require Hill offices to interview at least one minority staffer for each opening.

“Diversity has to be deliberate, and a systematic way to get members and chiefs out of their comfort zone during the interview process is to utilize the Rooney rule,” Jones said.