President-elect Donald Trump announced on Tuesday that hes chosen Exxon Mobil CEO Rex Tillerson as his secretary of state.

Rex Tillersons career is the embodiment of the American dream. Through hard work, dedication and smart deal making, Rex rose through the ranks to become CEO of Exxon Mobil, one of the worlds largest and most respected companies, Trump said in a statement.

His tenacity, broad experience and deep understanding of geopolitics make him an excellent choice for Secretary of State.

The Associated Press and The New York Times reported earlier that the president-elect had picked the oil chief, who has close ties to Russia. Trump had met with Tillerson in New York City on Saturday and tweeted Monday that he would make an official announcement on Tuesday morning.

Several members of Congress, both Democrat and Republican, expressed concern about Tillersons ties to Russia. They included Sen. Lindsey Graham (R-S.C.), who said he has many questions about Tillersons opposition to Russian sanctions.

I look forward to meeting Mr. Tillerson and discussing his world view especially his views of the US-Russian relationship, Graham said in a statement. 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. I expect the US-Russian relationship to be front and center in his confirmation process.

Sen. John McCain (R-Ariz.) told Reuters on Tuesday that he has concerns with the choice of Tillerson, saying its very well known that he has a very close relationship with Vladimir Putin.

Sen. Marco Rubio (R-Fla.) echoed the sentiment . 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 Americas interests, and will be a forceful advocate for Americas foreign policy goals to the president, within the administration, and on the world stage, Rubio said.

Rep. Eliot Engel (D-N.Y.), who is the ranking Democrat of the House Committee on Foreign Affairs, said in a statement that Tillersons cozy ties to Vladimir Putin and Russia would represent an untenable conflict at the State Department.

Kremlin spokesman Dmitry Peskov praised Tillerson on Monday. Peskov said the CEO acted highly professional while working previously with Kremlin representatives on oil company business.

Peskov said Tillerson, whos been Exxons CEO since 2006, has met with Russian President Vladimir Putin several times. Putin awarded Tillerson the countrys Order of Friendship in 2013 .