Opponents of the Tiahrt Amendments say these rules are making it more difficult than it should be to trace guns used in criminal acts. The letter from House Democrats said Obama's budget should defund them for that reason.

"For nearly a decade, these harmful restrictions have hindered law enforcement's ability to enforce existing gun laws, preventing law enforcement and public officials from cracking down on gun trafficking and gathering critical information in ongoing criminal investigations where illegal guns are used," they wrote.

Honda said this week that the Tiahrt Amendments are policy riders that have never been subject to a separate vote in Congress.

"I have worked for years on the Appropriations Committee to repeal these amendments and believe that now is finally the time to put common sense reforms in place to stop the flow of illegal guns and end the violence," Honda said this week. "We must now ensure that the FY14 budget is clean of this language, which has never had a floor vote or a full debate."

Defunding the Tiahrt Amendments in Obama's budget would have no immediate impact, because Obama's budget proposal is just that — a proposal to Congress. In addition, both the House and Senate approved their separate budget plans last week.

The White House announced today that Obama's budget would be released April 10, more than two months after the legal deadline.

The Democratic request to Obama came just days before Obama delivered remarks on Thursday urging Congress not to forget the shooting deaths of 20 elementary school children in Newtown, Conn.

But while Obama has proposed a new assault weapons ban and limits on large capacity ammunition magazines, Senate Majority Leader Harry ReidHarry Mason ReidMcConnell not yet ready to change rules for Trump nominees The Hill's Morning Report — Sponsored by CVS Health — Trump’s love-hate relationship with the Senate Trump to press GOP on changing Senate rules MORE (D-Nev.) has already said those proposals don't have enough support in the Senate.