WASHINGTON - U.S. Senate Democrats are introducing a measure to provide up to $400 million in new federal funding to replace and fix lead-contaminated pipes in the city of Flint, Michigan.

The bill also requires federal action if a state refuses to warn the public about unsafe water and authorizes $20 million a year to monitor lead exposure in Flint.

Democratic Sens. Gary Peters and Debbie Stabenow of Michigan were expected to offer the measure Thursday as an amendment to a Senate energy bill.

Flint's water became contaminated when the financially-struggling city switched from the Detroit municipal system and began drawing from the Flint River in 2014 to save money.

Regulators failed to ensure the water was treated properly and lead from pipes leached into the supply, leading to a spike in child lead exposure.