WASHINGTON (AP) — A Democratic Minnesota congressman is introducing a constitutional amendment designed to overturn the Supreme Court's decision in the Citizens United case that lifted many restrictions on corporate spending in political elections.

Rep. Rick Nolan unveiled the proposal on Monday along with members of Move to Amend, a grassroots coalition that has been seeking support on the local level in communities for the amendment. They say political campaign spending should not be a form of speech protected under the First Amendment.

The 2010 Citizens United ruling paved the way for a flood of campaign cash from corporations, unions and wealthy interests.

Any effort to amend the U.S. Constitution faces daunting hurdles.

Supporters of the Citizens United decision say it upholds the First Amendment guarantee of free speech.