(CNN) - Democratic Sen. Tim Kaine of Virginia said Sunday on CBS's "Face the Nation" that he will vote against former CIA Director Mike Pompeo for secretary of state because of what Kaine called the nominee's "anti-diplomacy disposition."
"We have a president who is anti-diplomacy," Kaine said. "And I worry that Mike Pompeo has shown the same tendency to oppose diplomacy."
Kaine cited Pompeo's opposition to the Iran nuclear deal when he was a member of the House of Representatives and said Pompeo "spoke about the relative ease of wiping out Iran's nuclear capacity with a bombing run."
In a written statement released after his appearance on CBS, Kaine called such a move "an unrealistic scenario" and wrote that Pompeo also "stands out in advocating US action to change out the governments" of North Korea and Iran.
Kaine said he voted for Pompeo to become CIA director because he thought his intelligence background made him well-suited for the position, but he is now voting against him for secretary of state because he does not want someone who is going to "exacerbate President Donald Trump's weaknesses rather than uphold our diplomatic legacy."
"You've seen President Trump try to underfund the State Department in USAID, not appoint key ambassadors, tweet out insults about foreign leaders, back the United States out of international agreements and organizations," Kaine said.
"We need a secretary of state who is going to stand up for strong diplomacy," he added, "and I don't believe that is Director Pompeo's inclination."
Several lawmakers expressed doubts about Pompeo after his confirmation hearing before the Senate Foreign Relations Committee on Thursday.
"There are fundamental areas of disagreement that we have, and I think that was true in the questioning," Senator Jeanne Shaheen of New Hampshire said in an interview with CNN after the hearing. "So he answered some of those questions but from my perspective, he just gave the wrong answers."
Republican Rand Paul also told CNN the hearing "really solidified" his opposition to Pompeo.
If Paul and Shaheen join Kaine in voting "no," Pompeo won't have enough votes to win a favorable recommendation from the committee. According to the Senate historian's office, there are no instances of a secretary of state nominee receiving an unfavorable committee vote since 1925.
But in an extraordinarily rare move, Senate Majority Leader Mitch McConnell could still bring up the nomination on the floor of the Senate despite the negative vote in the committee. If that would occur, Pompeo would need the support of at least one Democratic senator, given Paul's opposition and the continued absence of Sen. John McCain, who is recovering from brain cancer. And behind the scenes, Pompeo has been working to lock down support from moderate Democrats, including ones in tough races, to push him through on the floor.