The Senate has a practice of allowing individuals to put"holds" on legislation and nominations that forestall agreements to debate and vote on the matters. The party leaders honor the holds of their members because otherwise they might be voted out of the leadership.
For several months, a Texas Senator who favors selling Taiwan fighter jets built in the Lone Star state has been blocking action on a senior Defense Department nominee. There are now other DOD nominees in line to be voted on, when and if the hold is lifted. On Friday the White House sent a letter that seems to say it will sell new jets to Taiwan, and the hold is expected to be lifted.
I find this pretty deplorable, but that's the way Senators use their leverage over the Executive Branch. The worst part is that successful hostage taking encourages the practice.