Or at least President Joe Biden (D) is too timid to say so out loud, or officially, which would bring a round of additional sanctions against Russia.

Biden, asked by a reporter on Monday if he would blacklist Russia as a terrorist state, said simply, “no,” after months of non-committal answers from senior officials.

Biden expanded on that the next day, through his Press Secretary, Karine Jean-Pierre:

She said the designation would hamper aid delivery to parts of war-ravaged Ukraine or prevent aid groups and companies from taking part in a deal brokered by the United Nations and Türkiye to ship badly needed grain from Ukraine’s blockaded ports.
“It would also undercut our unprecedented multilateral [coalition] that has been so effective to holding Putin accountable and could also undermine our ability to support Ukraine” in negotiations, she told reporters.

In other words, Biden is afraid of what Putin might do in response to such a designation. Or worse, Biden is afraid of his own imaginings of what Putin might do.