Washington — Congress looks increasingly likely to vote on a bill that would allow the US Department of Justice to sue OPEC for antitrust violations, several sources said Friday.

Versions of the bill, titled the No Oil Producing and Exporting Cartels or NOPEC Act, have been introduced in every Congress over the past 20 years, but several current factors have fueled speculation that the Republican-controlled House and Senate may vote on it before the holiday recess, these sources said.

Several sources said, while not definite, talk of a potential vote on the NOPEC bill ramped up considerably as this week's OPEC meeting was taking place in Vienna.

"There's some push to look at NOPEC, but there's nothing certain yet," one House aide involved in talks to move the legislation said Friday.

Several analysts said that a congressional push to confront Saudi Arabia over the killing of journalist Jamal Khashoggi and its war in Yemen, as well as President Donald Trump's likely displeasure over OPEC's decision to cut production, have boosted the odds of a NOPEC vote.

"This will be one of those 'end of session, the president calls for it and congress answers' kind of deals," one analyst said. "It's not a sure thing, but there's momentum clearly there."

The bill, which would require passage in the House and Senate and Trump's signature to become law, would allow the US attorney general to sue a foreign crude producer for price manipulation under the Sherman Antitrust Act.

One analyst said the likely catalyst for a congressional vote on the NOPEC bill will be public support from the US DOJ.

In August, Senator Chuck Grassley, an Iowa Republican and chairman of the Senate Judiciary Committee, and US Representative Bob Goodlatte, a Virginia Republican and chairman of the House Judiciary Committee, sent a letter to Makan Delrahim, an assistant attorney general in DOJ's antitrust division, asking for his "views" on the NOPEC legislation. Delrahim has yet to respond, according to sources, but in 2008, as an attorney in private practice, he wrote an op-ed in The Hill newspaper in support of NOPEC legislation.

"There is simply no reason to treat cartel members differently based on their connection to a national government," Delrahim wrote. "Whether they involve Venezuela or Exxon Mobil, anti-competitive agreements cause significant harm to the world economy."

Delrahim is scheduled to appear before a House Judiciary subcommittee hearing on oversight of the antitrust enforcement agencies on Tuesday afternoon.

OPEC officials have grown increasingly uneasy about the prospects of NOPEC passage and, earlier this year, began devising a legal strategy to counter the legislation, sources said.

Sources speculated Friday that Qatar's surprising decision to withdraw from OPEC may have been partly motivated by concern over legal risk if the NOPEC legislation was signed into law. Qatar Petroleum is the majority owner of the Golden Pass LNG terminal in Texas.

"We left because it is our decision and our assessment is that it's not good for Qatar to remain [in OPEC]," Saad Sherida al-Kaabi, Qatar's energy minister, told reporters in Vienna Wednesday. "We don't see the value added for Qatar to remain."

Representative Steve Chabot, an Ohio Republican, introduced the House-version of the NOPEC bill, H.R. 5904, in May. It was approved by the House Judiciary Committee by voice vote in June. Grassley introduced the Senate-version of the NOPEC bill, S. 3214, in July. It has yet to be voted on by the Senate Judiciary Committee.

-- Brian Scheid, brian.scheid@spglobal.com

-- Herman Wang, herman.wang@spglobal.com

-- Edited by Annie Siebert, newsdesk@spglobal.com