U.S. President Donald Trump congratulates Jeff Sessions after he was sworn in as U.S. Attorney General as his wife Mary Sessions looks on during a ceremony in the Oval Office of the White House in Washington, D.C., Feb. 9, 2017. Reuters

Democratic lawmakers are calling on Attorney General Jeff Sessions to resign the job he's had for less than a month after it was revealed that he had a private meeting with the Russian ambassador in September, a meeting he did not disclose when asked about communications with the Russians during his January confirmation hearing.

After the Washington Post revealed Wednesday that then-Senator Sessions met with Russian ambassador Sergey Kislyak in his Senate office in September, Rep. Elijah Cummings (D-MD), the ranking member on the House Oversight and Government Reform Committee, called for Sessions to resign his post as the nation's top law enforcement officer.

"It is inconceivable that even after Michael Flynn was fired for concealing his conversations with the Russians that Attorney General Sessions would keep his own conversations secret for several more weeks," Cummings said in a statement released Wednesday evening. "Attorney General Sessions should resign immediately, and there is no longer any questions that we need a truly independent commission to investigate this issue."

Sessions released a statement Wednesday in which he said he "never met with any Russian officials to discuss issue of the campaign. I have no idea what this allegation is about. It is false."

The U.S. intelligence community released a report in January that said Russians hacked Democratic officials and spread misinformation with the goal of helping President Donald Trump win last year's presidential election. At a Jan 10. confirmation hearing, Sen. Al Franken (D-MN) asked Sessions what he would do if he found out any member of the Trump campaign communicated with the Russians during last year's presidential election.

“I’m not aware of any of those activities,” said Sessions, who was the first sitting senator to endorse Trump's presidential run. “I have been called a surrogate at a time or two in that campaign and I did not have communications with the Russians," he added.

Sessions also spoke with Kislyak in July, the Post reported. Justice Department officials told the Post that Sessions met with Kislyak as a member of the Senate Armed Services Committee, and not as a member of Trump's campaign.

While Sessions's camp argued that meeting with ambassadors was a regular part of the role of the Senate Armed Services Committee, Senator Claire McCaskill (D-MO), who also serves on the committee, tweeted Thursday morning that she hasn't met with or spoken with the Russian ambassador over the course of 10 years serving on the panel.

While Republicans stopped short of asking Sessions to resign, some Republican lawmakers did call for Sessions to remove himself from any investigations into Russian hacking or coordination between the Russians and the Trump campaign. On Thursday morning, Jason Chaffetz (R-UT), the chairman of the House Oversight and Government Reform Committee, tweeted that Sessions should "recuse himself."