Kentucky state Rep. Charles Booker has officially filed to enter the Democratic primary for the seat held by Republican Senate Majority Leader Mitch McConnell.

Booker is a freshman state lawmaker.

He joins a crowded field of Democrats competing to challenge McConnell, a key ally of President Donald Trump.

McConnell is seeking a seventh term this year.

Booker said Wednesday he's ready to take on the establishment in both political parties.

Amy McGrath, a retired Marine combat pilot, has raised nearly $17 million and is widely seen as the frontrunner for the Democratic nomination.