An Illinois congressman who decorated his office in a style modeled after the TV show "Downton Abbey" may face an ethics investigation. 

A watchdog group has asked a congressional review panel to examine whether Republican Rep. Aaron Schock broke House rules by accepting professional interior design work for free. Citizens for Responsibility and Ethics in Washington, a nonpartisan watchdog group, requested an inquiry by the Office of Congressional Ethics, an outside panel that reviews ethics complaints against House members. 

But Schock told ABC News Wednesday that he paid Brahler about $6,000 to decorate his office four years ago and will pay her again this year once he receives an invoice. He used a personal check last time and expects to do so again, Schock said. 

A spokesman for Schock declined to comment, as did the Office of Congressional Ethics and the House Ethics Committee. 

The Washington Post reported this week that interior decorator Annie Brahler donated her services as she decorated Schock's Washington office with a red carpet and walls accented with antique-looking frames and sconces reminiscent of "Downton Abbey." The popular PBS show depicts the lives of aristocratic family and their servants in 1920s England. 

"Perhaps it's not totally surprising that the same congressman who spent campaign money on P90X workout DVDs wanted to create a more picturesque setting in which to be photographed, but the rules clearly require him to pay for those renovations himself," said Anne Weismann, the watchdog group's interim executive director. 

House rules broadly prohibit members of Congress from accepting gifts or services valued at more than $50. The rules include numerous exemptions, including one that allows gifts from personal friends. 

Brahler, who owns an Illinois-based firm called Euro Trash, also decorated Shock's previous Washington office, the Post reported. 

While the decorations have drawn comparisons to "Downton Abbey," Schock said he has never seen the show. 

Schock, 33, is in his fourth term representing the Peoria and Springfield areas. He cited pop singer Taylor Swift in brushing off the controversy over his office decor. "Haters are gonna hate," he said. 

The Ethics Committee has said it is continuing an investigation into allegations that Schock violated federal law and House rules by soliciting donations of more than $5,000 per donor to a super political action committee that backed an Illinois colleague in 2012. 

The Office of Congressional Ethics said in a 2013 report that there is reason to believe Schock violated House rules by soliciting campaign contributions for a committee that backed Rep. Adam Kinzinger, R-Ill., in a 2012 House primary. The investigation remains open, the Ethics Committee said Wednesday. 

A spokesman for Schock in 2013 said the congressman had done nothing wrong.