President Trump’s nominee for secretary of state marched closer Monday to winning confirmation, as a key Senate panel advanced his nomination and a major Republican holdout backed him.

Rex Tillerson’s cautious embrace by Capitol Hill Republicans marks an unexpected marriage between Trump and traditional GOP hawks, who have long been at odds on foreign policy. It’s an alliance that would have seemed unlikely during the presidential campaign, but as Trump has ascended to power, his party has increasingly acquiesced to his idea of what it means to be a Republican.

Tillerson, the former chief ­executive of ExxonMobil, won the support of the Senate Foreign Relations Committee in an ­11-to-10 vote along party lines. His nomination to be the nation’s top diplomat now heads to the full Senate, where he is expected to win final confirmation next week with little drama.

Tillerson’s approval comes even as congressional Republicans have promised to investigate charges by the intelligence community that Russia interfered in the November election in an attempt to benefit Trump.

The Senate Intelligence Committee has started to look into the intelligence community’s probe of a potential relationship between Trump and Russia, which could complicate the fragile alliance Republicans have been forging with the president on overseas matters.

Sen. Marco Rubio (R-Fla.) voiced reservations about Rex Tillerson’s nomination but eventually voted for him. (Matt McClain/The Washington Post)

Republicans had been concerned about Tillerson’s own ties to Russia and President Vladimir Putin, given the extensive amount of business he did in the country as the head of a large company. Several senators also questioned whether the businessman would be committed enough to maintaining sanctions against Russia as secretary of state, given how he has criticized the way those punitive measures were implemented.

Sen. Marco Rubio (R-Fla.), who had expressed serious doubts about Tillerson largely because of his ties to Russia, was among those voting in favor of him. Rubio voiced his support in a lengthy written statement Monday morning, the day after Sens. John McCain (R-Ariz.) and Lindsey O. Graham (R-S.C.), two other skeptics, announced they would vote for the businessman.

While Tillerson’s confirmation was effectively guaranteed Sunday when McCain and Graham gave him their support, Rubio’s decision provided a further boost from a former presidential candidate and spared Rubio a potentially embarrassing show of defiance.

Since late last year, the Florida Republican had voiced substantial concerns about Tillerson. After the vote, Rubio said his reservations were broader than Tillerson’s ties to the Russian government.

“My concern was that Tillerson would be an advocate for and pursue a foreign policy of deal-making at the expense of traditional alliances,” the senator said.

Rubio said one consideration in his final decision was his belief that presidents are entitled to some leeway on whom they want to put on their teams.

Rubio was getting an onslaught of calls, texts and notes urging him to back Tillerson, those close to him said.

Rubio donors and other supporters who served as Tillerson boosters — including many from the nominee’s home state, Texas — reached out early and often to try to nudge the senator to back Tillerson. Rubio heard from former vice president Richard B. Cheney late last year.

Last week, Rubio held a meeting with Tillerson, now-Vice President Pence and now-White House Chief of Staff Reince Priebus, according to two people familiar with the meeting. The people spoke on the condition of anonymity to describe the private gathering.

The general acceptance of Trump’s Cabinet nominees — despite potential conflicts of interest from some of them who have backgrounds as businessman — shows that most Republicans are allowing Trump a generous amount of room to pick the officials with whom he wants to work.

“While there are differences in some policy areas between some members of the Senate and some of these nominees, the tradition, and in this case the practice, is to allow the president to pick,” said Michael Steel, who was an adviser to Jeb Bush in his presidential campaign.

Democrats complained that Tillerson had not submitted his tax returns to the committee and urged a change in policy to require such paperwork in the future. And they expressed frustration that Tillerson had not given specific answers to many of the more than 1,000 questions to which he responded.

“I’ve looked at those responses, and they’re not responses to the questions that are asked,” Sen. Benjamin L. Cardin of Maryland, the ranking Democrat on the Foreign Relations Committee, said.

Senate Foreign Relations Chairman Bob Corker (R-Tenn.) defended Tillerson and accused Democrats of “asking silly, silly, ridiculous, elementary questions that have nothing to do with somebody serving as secretary of state.” He added that he hopes the committee does not adopt a policy of asking for nominees’ tax returns in the future “because most of those are used for gotcha questions.”

The vote on Tillerson was the first big test of how Rubio plans to deal with Trump, with whom he clashed in the campaign. By voting yes, Rubio spared himself what his allies anticipated would have been an angry backlash from the new administration in private.

But at the end of his written statement, Rubio added a note of warning: “Upcoming appointments to critical posts in the Department of State are not entitled to and will not receive from me the same level of deference I have given this nomination.”

Rubio, McCain and Graham all belong to the hawkish wing of the Republican Party, with views that have been mainstream in the GOP for many years. But Trump has upended that with his praise for Putin and far less hostile posture toward the Russian government.

Rubio said that while he found some of Tillerson’s responses to his questions encouraging, he remained troubled by others, including his unwillingness to say Putin had committed war crimes.

Senate Intelligence Committee leaders said this month that they would probe allegations of links between Russia and the 2016 campaign, including claims of ties between Trump’s campaign and the Russian government.

Cardin said at Monday’s vote that he was not comfortable with some of Tillerson’s answers on Russia and other matters.

“I did not see that commitment to be an advocate globally for human rights and global governance that I would like to see in a secretary of state,” he said.

Monday’s committee vote on Tillerson came amid a push by Republicans to swiftly confirm Trump’s nominees. Speaking on the Senate floor, Majority Leader Mitch McConnell (R-Ky.) called on his Democratic colleagues not to obstruct the confirmation of Trump’s nominees.

But Senate Minority Leader Charles E. Schumer (D-N.Y.) accused of Republicans of trying to “ram though” confirmations.

.After several hours of debate Monday, the Senate confirmed Rep. Mike Pompeo (R-Kan.) to be head of the CIA on a 66-to-32 vote. Republican leaders had sought to hold a confirmation vote for him on Trump’s first day in office, but some Democrats forced the extended debate.

The Foreign Relations Committee is scheduled to vote Tuesday on South Carolina Gov. Nikki Haley (R), Trump’s nominee for ambassador to the United Nations. Haley is expected to win confirmation easily.

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