Donald Trump. Tom Pennington/Getty Images Sen. Jeff Sessions of Alabama endorsed Republican presidential frontrunner Donald Trump's campaign on Sunday.

Trump announced the endorsement alongside Sessions at a massive campaign rally in Madison, Alabama.

"At this time in America's history, we need to make America great again!" Sessions said, echoing Trump's campaign slogan. "I am pleased to endorse Donald Trump for the presidency of the United States."

Sessions, known for his hard-line stance against illegal immigration, is popular in some conservative circles.

Trump's presidential rival Sen. Ted Cruz of Texas has frequently invoked Sessions to defend his record on immigration. On Sunday, Drudge Report founder Matt Drudge called Sessions the "conservative soul" of the US Senate.

Several other notable politicians have also recently thrown their support to Trump, though another GOP candidate, Marco Rubio, has grabbed the lion's share of recent endorsements from elected officials.

Gov. Chris Christie of New Jersey, who exited the presidential race earlier this month, endorsed Trump on Friday. And former Gov. Jan Brewer of Arizona, whose record on illegal immigration once caused a national firestorm, announced her support for Trump on Saturday.

The Trump campaign emailed reporters the following statement hailing Sessions' endorsement:

Today Donald J. Trump received the endorsement of Alabama Senator Jeff Sessions. Senator Sessions is widely recognized as the nation's most highly respected official on the issue of illegal immigration.

Mr. Trump stated, "I am deeply honored to have the endorsement of Senator Jeff Sessions, leader of congressional conservatives. He has been called the Senate's indispensable man and the gold standard. He led the fight against the Gang of Eight, against Obama's trade deal, against Obama's judges, and for American sovereignty. He has stood up to special interests as few have. There is no more respected man in Congress and we are closely aligned on many issues, including trade and illegal immigration, and I am proud to consider Jeff Sessions an advisor, friend and ally."

Mr. Trump and Senator Sessions surprised the massive crowd at the frontrunner's Alabama rally just days before Super Tuesday Primary contest.

Senator Sessions added, "I am thrilled today to offer my endorsement of Donald J. Trump for President. This election is our last chance to save U.S. sovereignty and to end the domination of the political establishment over the interests of working Americans. Trump alone has rejected the donor class, defending America's jobs and wages from open borders, uncontrolled immigration and the massive Trans-Pacific Partnership that will cede U.S. authority to foreign powers. Trump's trade and immigration plans will revitalize our shrinking middle class, keeping jobs and wealth and income inside the United States of America. Trump understands that a nation must always place the interests of its own people first."

Senator Sessions continued, "We are nearing fast the point of no return. The people are hurting. Their wages are declining. Their schools are overburdened. Their hospitals are stretched past the breaking point. Crime is up, and community confidence is down. Americans of all backgrounds and ethnicities, immigrant and US-born, are crying out for leadership that puts their needs first, that takes care of those living and dreaming here today, leadership that understands that there is no constituency other than the American constituency. Mr. Trump is that leader.

We are witnessing an incredible movement, arising from the people.

The events of history have aligned to give the people this fleeting chance to bust up the oligarchy – to take back control from the 'Masters of the Universe' return it to the good and decent and patriotic citizens of the United States."