The IRS admitted last week that it was targeting conservative groups with the words "tea party" and "patriot" in their names, often probing to ensure these groups qualified for tax-exempt status.

"I am confident that President Obama will work to get to the bottom of this and ensure that all those responsible for wrongdoing are held fully accountable, and I urge him to begin this review immediately," Cicilline added.

A handful of Democratic senators have criticized the IRS for discriminating against groups based on ideology, but very few House Democrats have. Of the 16 Democrats on the House Way & Means Committee, which has jurisdiction over tax legislation, none of them had issued a formal statement on the controversy as of Monday morning.

Ways & Means Chairman Dave Camp (R-Mich.) has said he'd hold a hearing on the issue later this month. Rep. Charles BoustanyCharles William BoustanyDems face hard choice for State of the Union response Americans worried about retirement should look to employee ownership Top Lobbyists 2017: Hired Guns MORE (R-La.), who chairs the subcommittee on Oversight, has demanded information from the IRS on its targeting of conservative groups.