MONTGOMERY, Ala. (AP) – Alabama has a new law to prevent voters from switching parties between a primary and subsequent runoff.

The law prohibits voters from casting a ballot in one political party’s primary and then voting in the other party’s primary runoff.

Republican Sen. Tom Whatley said it will prevent voters of one political party from trying to interfere in another party’s runoff. Whatley sponsored the measure.

Gov. Kay Ivey signed the measure into law after its approval by the Alabama Legislature.

Secretary of State John Merrill said the law will be in place for an anticipated September runoff in the crowded race for the U.S. Senate seat previously held by Sen. Jeff Sessions.

Whatley has pushed the legislation for three years.