“I do not make this decision lightly or without reservations," Coons said in a statement. "I remain concerned that Director Pompeo will not challenge the President in critical moments. On vital decisions facing our country, Director Pompeo seems less concerned with rule of law and partnership with our allies and more inclined to emphasize unilateral action and the use of force."
Coons also said he was concerned with some of Pompeo's past statements made over his political career on "a range of issues."
But with Coons’ announcement, all ten Democrats on the committee have now announced that they would not support Pompeo.
Coons’ position is not a surprise. He had said as late as Thursday afternoon that he was “leaning against” Pompeo's nomination and he also voted against him to serve as CIA director last year.
The Senate Foreign Relations Committee will vote on Pompeo’s nomination Monday.
With the option of a favorable recommendation off the table, they can still report the nomination to the Senate floor with an unfavorable recommendation or simply take no action. And the full Senate will still vote on his confirmation, which is likely to succeed.
But the fact that Pompeo’s confirmation will not be referred favorably to the full Senate is an almost unprecedented rebuke from the committee of jurisdiction. The last time any cabinet-level nominee who was reported unfavorably by a committee but went on to be confirmed by the full Senate was 73 years ago when Henry Wallace was confirmed to be the secretary of commerce on March 1, 1945.
If no other Republican besides Paul opposes Pompeo in the Senate floor vote, Heitkamp’s support means he will have just enough votes to be confirmed, including Vice President Mike Pence’s tie-breaking vote.
ABC's Mariam Khan contributed to this report.