President Donald Trump took to social media Tuesday to restate his support for Alabama Sen. Luther Strange ahead of next week's Republican runoff between Strange and Roy Moore, the state's former chief justice.

"Alabama is sooo lucky to have a candidate like 'Big' Luther Strange," Trump tweeted. "Smart, tough on crime, borders & trade, loves Vets & Military. Tuesday!"

The president later called on gun owners in Alabama to vote for Strange, citing the endorsement of the National Rifle Association.

Trump and Vice President Mike Pence are scheduled to headline campaign events for Strange over the next few days. The president will attend a rally at the Von Braun Center in Huntsville Friday, while Pence will head to Alabama on Monday.

Strange and Moore are battling to fill the seat vacated by Jeff Sessions, who resigned to become Trump's attorney general earlier this year. Polls have consistently shown Strange trailing Moore, despite the backing of Trump, Pence and Senate Majority Leader Mitch McConnell, R-Ky.

Moore is a darling of Alabama's evangelical voters after twice being removed from office over stands against gay marriage and for the public display of the Ten Commandments. Moore also has the backing of the pro-Trump Great America Alliance and House Freedom Caucus member Rep. Mo Brooks, who finished third behind Moore and Strange in last month's GOP primary.

The Associated Press contributed to this report.