The Federal Trade Commission building is seen in Washington on March 4, 2012. REUTERS/Gary Cameron

WASHINGTON (Reuters) - Three members of the Federal Trade Commission were sworn in on Wednesday, bringing the agency to full staffing at the top for the first time since mid-2015.

Chairman Joe Simons, a Republican, had been sworn in late Tuesday. On Wednesday, Republican Noah Phillips was sworn in along with Democrats Rebecca Slaughter and Rohit Chopra.

The fifth member of the commission, Republican Maureen Ohlhausen, had been acting chairwoman for the past 15 months and will stay on until her term ends in September or until she is confirmed to a federal judgeship.

The Senate has also confirmed Republican Christine Wilson, a senior vice president for regulatory and international affairs at Delta Air Lines Inc, to replace Ohlhausen once she departs.

The FTC has not had five commissioners since Josh Wright, a Republican, stepped down in mid-2015, according to FTC data.

The FTC works with the U.S. Justice Department to enforce antitrust law and investigates companies accused of deceptive advertising. One big merger before it currently is a proposed combination of industrial gases companies Praxair Inc PX.N and Linde AG LING.DE.

It is also reviewing whether Facebook FB.O violated a 2011 FTC consent decree over its privacy practices following allegations that Cambridge Analytica improperly gained access to user data for 50 million people without users being notified.