A pro-Trump super PAC plans to initiate a digital advertising campaign in support of GOP Sen. Luther Strange for next week's Alabama Senate special election primary.

America First Action announced Friday it will spend between $150,000 and $200,000 to help Strange, whom President Trump endorsed earlier this week.

The campaign will target Trump supporters in Alabama, a state the president easily carried in the 2016 election.

"As the pro-Trump super PAC, we are proud to join the president in supporting the candidacy of Sen. Luther Strange, a tireless public servant and defender of the First and Second Amendment rights of his fellow Alabamians," said Erin Montgomery, a spokeswoman for the group, in a statement. "Sen. Strange has already proven himself to be the best possible candidate in this race to stand beside our president and make America great again."

Trump's endorsement of Strange surprised observers of the race to fill the seat vacated by Attorney General Jeff Sessions.

Strange was appointed in February to fill Sessions' seat and has become an ally of Senate Majority Leader Mitch McConnell, R-Ky. Trump has furiously criticized McConnell this week for the GOP's failure to repeal Obamacare.

Strange is competing in the Republican primary against Rep. Mo Brooks, R-Ala., a member of the conservative House Freedom Caucus, and former state Supreme Court Justice Roy Moore.

There are seven candidates in the Democratic primary.

One of the Democrats, Doug Jones, a former federal prosecutor, earned the endorsement of former Vice President Joe Biden on Thursday.