Republican leaders fear that candidates who are too far to the right could lose to Democrats, who are seeking to wrest control of the House and the Senate in the 2018 midterm elections.
Moore, Alabama's former Supreme Court justice, has been polling ahead of unusual, who is favored by Senate majority leader Mitch McConnell.
"If his opponent wins, I'm going to be here campaigning like hell for him", Trump said. Still, he bemoaned that if odd loses, he'll be unfairly blamed in the press for the defeat.
Trump's use of Twitter dates back years before he was in the White House and has been one of the more unique and controversial aspects of his presidency.
Trump also predicted that any owner who followed the presidential encouragement would become "the most popular person in this country" - at least for a week.
Unusual is trying to ward off a challenge from Roy Moore, a conservative former state Supreme Court justice, in a runoff election next week.
"If Luther doesn't win, they're not going to say we picked up 25 points in a very short period of time".
Trump's involvement in the Alabama race could help bolster his strained relationship with Senate Majority Leader Mitch McConnell, whose help the president needs to advance his agenda on taxes, healthcare and immigration. But even at times, some of those assertions seemed downright implausible.
The six-foot-nine odd, who Trump said he had taken to calling "Big Luther", faces a hard road to victory in Tuesday's primary. The Washington Post reported that many supporters who packed the Von Braun Center were only there to see Trump and told the newspaper that they planned to vote for Moore.
Trump repeatedly praised unusual and often calling the 6'9ft senator "Big Luther".
Trump allies say he is genuinely appreciative of Strange's loyalty and support.
Moore bashed odd for following that high court ruling as Alabama's attorney general. The governor eventually resigned. He criticized Sen. John McCain, R-Ariz., for opposing GOP efforts to repeal and replace former President Barack Obama's health care law. Trump said Republicans "don't have the guts to vote for it" now they have a president who will sign it. Sen.
"You know, I brand people", he said. Vice President Mike Pence also plans to campaign for unusual ahead of the runoff vote. At a debate with Moore on Thursday, Strange couldn't mention enough that he was Trump's chosen candidate.
Trump told the crowd in Huntsville that he will "handle" Kim unlike previous administrations before him.
Moore fired back that the "elitist Washington establishment" was spending millions of dollars to try to secure the race for odd while refusing to enact Trump's agenda. Most importantly, unusual is receiving a massive boost today with a visit from President Trump to Huntsville, AL. At times, he'd weave back in praise of odd, but his most animated moments were talking about some of his pet issues. He called the investigation into Russia's possible role "the Russian hoax". We don't need to go into it.
"If Luther didn't take an appointment, if he just ran, it wouldn't be a contest", Trump said.