Democratic and Republican lawmakers and politicians expressed support for Sen. John McCain on Wednesday night after his office revealed he has brain cancer.

President Trump praised McCain as a "fighter," and said he hopes McCain, R-Ariz., recovers soon.

"Senator John McCain has always been a fighter," Trump said in a statement. "Melania and I send our thoughts and prayers to Senator McCain, Cindy, and their entire family. Get well soon."

Former President Barack Obama, who competed against McCain, in the 2008 presidential election, called McCain an "American hero."

"John McCain is an American hero & one of the bravest fighters I've ever known," Obama tweeted. "Cancer doesn't know what it's up against. Give it hell, John."

Former Vice President Joe Biden, who also served with McCain in the Senate, has an acute familiarity with cancer. His son, Beau, died from brain cancer in 2015.

"John and I have been friends for 40 years," Biden said. "He's gotten through so much difficulty with so much grace. He is strong - and he will beat this."

Hillary Clinton, the 2016 Democratic nominee for president who served with McCain in the Senate, said her former colleague is "as tough as they come."

"John McCain is as tough as they come," Clinton tweeted. "Thinking of John, Cindy, their wonderful children, & their whole family tonight."

Sarah Palin, McCain's vice presidential running mate in 2008, remarked on Twitter that he would "face this diagnosis with courage and strength."

Vice President Mike Pence predicted that McCain will win his fight with cancer.

"Karen & I are praying for @SenJohnMcCain. Cancer picked on the wrong guy," Pence tweeted. "John McCain is a fighter & he'll win this fight too. God bless!"

House Majority Whip Steve Scalise, R-La., who remains hospitalized after being shot at the congressional baseball practice last month, referred to McCain as "the toughest person I know."

Speaker Paul Ryan, R-Wis., aimed to unite Democrats and Republicans around supporting McCain's recovery.

"John McCain has always been a warrior," Ryan said in a statement. "It's who he is. All of us, not as Republicans or Democrats, but as Americans, are behind him."

Senate Minority Leader Chuck Schumer, D-N.Y., said he knows McCain will beat cancer.

".@SenJohnMcCain, you are a true fighter & I'll be praying for you until you beat this," Schumer tweeted. "I know you will."

Senate Majority Mitch McConnell, R-Ky., commended McCain, a former prisoner of war, for his courage.

"John McCain is a hero to our conference and a hero to our country," McConnell said in a statement. "He has never shied from a fight and I know that he will face this challenge with the same extraordinary courage that has characterized his life."

Sen. Jeff Flake, R-Ariz., said he spoke with his Arizona counterpart.

"Just spoke to @SenJohnMcCain," Flake said. "Tough diagnosis, but even tougher man."

Sen. Angus King, I-Maine., in perhaps the most colorful statement, said he wished he could be with McCain tonight.

"I love John McCain," King tweeted. "I've traveled with him, I've been tongue lashed by him, I've worked with him, and I wish I could be with him tonight."

McCain, 80, was recently operated on to remove a blood clot from above his left eye. Tissue extracted during the procedure, described as successful, proved to be cancerous, according to a statement from the Mayo Clinic in Phoenix, where the senator is being treated, that was publicized by his office. Treatment options, including chemotherapy, are being reviewed.

An additional statement, from McCain's Senate office, said there was no timetable for his return to work in Washington.