WASHINGTON >> Legislation floated by two Democratic senators would enhance transparency for online political ads, requiring social media companies like Facebook and Twitter to keep a public file of them.

The bill by Sens. Mark Warner of Virginia and Amy Klobuchar of Minnesota would try to fill what they call a “major gap” in election advertising transparency.

In a letter obtained by The Associated Press, the two say the legislation would also require companies to “make reasonable efforts” to ensure that election ads are not purchased directly or indirectly by foreign nationals.

The letter was sent today, the same day Facebook said it will provide the contents of 3,000 ads bought by a Russian agency to congressional investigators and make political advertising on its platform more transparent.