Republicans who have long stood hard against Russia and President Vladimir Putin Tuesday widely praised President-elect Donald Trump's pick for secretary of state, Exxon Mobil CEO Rex Tillerson, as strong corporate executive who understands the challenges facing the United States on many fronts around the world.

They include Dick Cheney, Bob Gates, Condoleezza Rice, Donald Rumsfeld, James A. Baker III and Jeb Bush.

However, several key GOP senators — Marco Rubio of Florida, John McCain of Arizona and Lindsey Graham of South Carolina — expressed concerns about Tillerson's close ties to Russia.

"He would bring to the position vast knowledge, experience and success in dealing with dozens of governments and leaders in every corner of the world," Gates said of Tillerson. "He is a person of great integrity whose only goal in office would be to protect and advance the interests of the United States."

Gates, a Trump adviser who has served as CIA director and defense secretary, acknowledged that Exxon Mobil was "one of many clients" of RiceHadleyGates, a consulting firm owned by him and Rice.

"Rex Tillerson is an excellent choice for Secretary of State," said Rice, who served as in the post under President George W. Bush. "He will bring to the post remarkable and broad international experience; a deep understanding of the global economy; and a belief in America's special role in the world."

Trump said Tuesday that he would nominate Tillerson, 64, who has helmed the world's largest oil company since 2006, to become the nation's top diplomat, saying that he was "one of the truly great business leaders of the world."

Tillerson said that he would work to restore America's credibility on the international stage.

"We must focus on strengthening our alliances, pursuing shared national interests and enhancing the strength, security and sovereignty of the United States," he said in a statement with Trump's announcement.

Cheney, the former two-term vice president, called Tillerson "an inspired choice."

"I've known Rex for many years both in his role as the chairman and CEO of Exxon Mobil and as a personal friend," he said. "He has the vast experience, ability, and judgment to deal with the very dangerous world we find confronting us.

"I'm confident that he will do a superb job promoting our national interests in dealing with the complex and difficult choices that are on the agenda for the next administration."

On Twitter, Rumsfeld, a defense secretary under two presidents, said:

W/ the addition of Tillerson, a talented exec & skillful negotiator, @realDonaldTrump seems to be assembling an accomplished & able cabinet. — Donald Rumsfeld (@RumsfeldOffice) December 13, 2016

Baker, who served as secretary of state under former President George H.W. Bush, said that Tillerson has "demonstrated the management and negotiating skills, and has the international experience, that are required for the job.

"I am confident that he will understand the global challenges facing the United States and has the intellect to address them."

Former Florida Gov. Jeb Bush, who quit the presidential race in February, praised Tillerson's "vast experience" and called him a "patriot."

The corporate executive will "represent the interests of United States really, really well," Bush told WJHL-TV in Kingston, Tenn.

However, the Senate "will have the chance to discuss all these things in an opening hearing," he cautioned. "That's how the process works."

These endorsements came as some senators voiced concerns about the Exxon Mobil CEO's ties to the Kremlin — dating back nearly two decades.

In 2013, Russia awarded Tillerson the Order of Friendship. He visited with Putin's inner circle two years later.

In 2011, he signed an agreement with Russia allowing Exxon Mobil to drill in the Arctic Ocean. The deal was valued at as much as $300 billion.

Neither McCain, Rubio, nor Graham has said that they would vote to confirm Tillerson when he comes up for nomination in the Senate, but they expressed reservations about his Moscow dealings.

Rubio said that while Tillerson was "a respected businessman, I have serious concerns about his nomination.

"The next secretary of state must be someone who views the world with moral clarity, is free of potential conflicts of interest, has a clear sense of America's interests, and will be a forceful advocate for America's foreign policy goals to the president, within the administration, and on the world stage."

The senator promised "a full and fair but also thorough hearing" for Tillerson when he comes before the Foreign Relations Committee.

If confirmed by the panel, Tillerson's nomination would be voted on by the full Senate.

Graham, who said last week that he was spearheading several investigations into Moscow because he wanted President Vladimir Putin "personally to pay a price," said that he looked forward to discussing Tillerson's "world view — especially his views of the U.S.-Russian relationship.

"Based upon his extensive business dealings with the Putin government and his previous opposition of efforts to impose sanctions on the Russian government, there are many questions which must be answered," Graham added. "I expect the U.S.-Russian relationship to be front and center in his confirmation process."

McCain told CNN Tuesday that "anybody who is a friend of Vladimir Putin must disregard the fact that Vladimir Putin is a murderer, a thug, and KGB agent, whose airlines, as we speak, have been targeting, with precision weapons, hospitals in Aleppo, who have committed atrocities throughout the region — and has destabilized Ukraine.

"The list goes on and on."

Other Republicans also lauded Trump's choice on Tuesday:

Senate Majority Leader Mitch McConnell of Kentucky:

"We need a full review of our national security policy, and I know Rex will face each problem head on with American interests and security as his top priority."

House Speaker Paul Ryan of Wisconsin:

"A proven leader and person of enormous accomplishment."

Senate Majority Whip John Cornyn of Texas:

"His experience will be critical as the next Secretary of State will face a broad array of diplomatic challenges that will define the security and success of our nation for generations."

Sen. Bob Corker of Tennessee, chairman of the Senate Foreign Relations Committee:

"Mr. Tillerson is a very impressive individual and has an extraordinary working knowledge of the world."

Sen. Jim Inhofe of Oklahoma:

"I am confident that he will leverage our global leadership position to strengthen the United States and our allies around the world."

Former House Speaker Newt Gingrich, who reportedly was being considered for the top diplomatic post:

"Getting Rex Tillerson to serve as Secretary of State is a great achievement by President elect Trump."