Several federal departments and agencies posted partisan messages on their websites and in out-of-office emails during the shutdown. Democrats believe the posts violate federal law.

A group of Senate Democrats is pushing for an investigation into the Trump administration’s use of federal agency websites and emails to post partisan messages blaming Democrats for the government shutdown.

In a letter obtained by NBC News, Sen. Elizabeth Warren of Massachusetts and other Democrats ask the Government Accountability Office to open a probe into whether the political messages violated federal appropriations laws.

The lawmakers point specifically to a rule that prohibits the executive branch from using funds for “purely partisan” purposes. They are asking for more information from the GAO to see if several agencies violated laws that pertain to ethics and partisan political activity.