MONTGOMERY (AP) — On the final day of campaigning in Alabama, U.S. Sen. Luther Strange on Monday touted his backing from President Donald Trump while his GOP rivals continued to batter him as the candidate of the so-called Washington establishment because of his bankrolling from Senate leadership.

Alabama voters go to the polls on Tuesday for party primaries in the race to fill Attorney General Jeff Sessions’ Senate seat. Despite Trump’s endorsement and the backing of millions of dollars in advertising by a super political action committee tied to Senate Majority Leader Mitch McConnell, Strange has found himself a tight primary against firebrand challengers, including former Alabama Chief Justice Roy Moore and U.S. Rep. Mo Brooks, a member of the House Freedom Caucus.

Trump recorded a message urging Alabama Republicans to vote for Strange, who was appointed earlier this year to temporarily fill Sessions’ seat.

Trump’s message was sent out as an automatic call to more than 150,000 households on the eve of the primary.

In the call, Trump says his administration is accomplishing many of his promises “but I need Luther to help us out.” The call came after Trump twice spoke of his support for Strange via Twitter.

“I feel like the momentum is on our side with the President’s tweet and robocall today. I think everything is looking great,” Strange said as he worked telephones at his campaign office.

Brooks on Monday said the race was an opportunity to send a “huge message” to the Senate leadership about the dysfunction in the U.S. Senate.

It would send “chills down the spine” of McConnell, Brooks said, for the race to end up in a runoff between himself and Moore.

Brooks spent the last two weeks crisscrossing the state on a bus nicknamed the “Drain the Swamp Express” that also had a “Ditch Mitch” sign secured to it.

In a campaign stop Monday, Brooks said he is the candidate with the strongest voting record for Trump’s agenda. Brooks said he, unlike Strange, supports Trump’s request to change Senate filibuster rules that make it easier for Democrats to defeat legislation.

Moore is often considered a contender in the race because of the fame he has gained as an icon of the culture wars.

Moore was twice removed from his duties over stances for the public display of the Ten Commandments and against gay marriage

“It’s a critical stage for our country. This is a prelude to the 2018 senatorial races. I think the Washington crowd is watching this race because it’s kind of a bellwether,” Moore said.

The Senate Leadership Fund, which has ties to McConnell, has saturated state airwaves with ads on behalf of Strange, with commercials aimed at keeping down support for both Moore and Brooks.

The crowded GOP field increases the odds that the race will end up in a September runoff between Tuesday’s top two finishers.

Other Republicans in the race include Sen. Trip Pittman and Christian Coalition leader Randy Brinson.

The rollicking primary began with Strange’s appointment in February by then-Gov. Robert Bentley, who later resigned in the cloud of a scandal.

Challengers have taken swipes at Strange for seeking an appointment from the governor when Strange, as attorney general, was in charge of an investigation.

Alabama Gov. Kay Ivey, immediately after taking office, announced the election would occur this year — instead of 2018 as Bentley planned— triggering a four-month demolition derby among contenders.

The Democratic side of Tuesday’s election is also crowded.

Doug Jones, a former U.S. attorney under the Clinton administration, is perhaps the best-known statewide in the field vying for the nomination and is backed by some national party figures such as former Vice President Joe Biden.

Other candidates include Michael Hansen, the head of an environmental organization who has urged Democrats to fully embrace progressive stances.

Robert Kennedy, Jr., a Navy veteran who is unrelated to the famed Massachusetts political dynasty, has urged Democrats to build bridges with Republicans and independents.

While Alabama has not elected a Democrat to the U.S. Senate in more than 20 years, some Democrats hope that a December special election — particularly if Republicans end up with a polarizing nominee — could give them at least a chance in the matchup between the winning Republican and Democrat.