Democrats also compared the move to the Republicans blocking funding for troops for political purposes.
As we reported earlier, DeMint blamed Reid for not allowing lawmakers to debate the nomination before adjourning.
Even Republicans who oppose the nomination believe Southers would be confirmed, and sources tell TPMDC he is highly qualified on counterterrorism issues and would have been useful had he been in place before the Christmas terror attempt.
Manley called DeMint "disgraceful."
Southers, nominated in September, passed out of two committees this fall.
A spokeswoman for Sen. Joe Lieberman's Homeland Security and Government Affairs Committee, which approved the nomination in November, said today that Lieberman believes the hold is "contrary to the public interest."
"The head of TSA is a key player in the government's efforts to safeguard the American people from terrorism," said the committee spokeswoman Leslie Phillips.
DeMint's concern is over the unionization issue, a topic that Southers would not give a clear answer to during his confirmation hearings.
A Senate source told TPMDC that Southers has maintained he is not not prepared to say he'll support or oppose unionization efforts "until he's confirmed, in place and hearing from stakeholders about the issue."
DeMint won't lift his hold, a Senate aide told TPMDC earlier today.
Senate Majority Whip Dick Durbin (D-IL) told his colleagues Dec. 22 that it was "irresponsible" the Southers nomination was being held.
"Unfortunately, without Chief Southers in the position he has been nominated to, TSA is without the leadership necessary to move forward," Durbin said on the Senate floor. "At the same time Senate Republicans are insisting on expanding the role and responsibility of TSA by requiring guns to be allowed on Amtrak, they block and delay the permanent leadership necessary to implement these new policies."
He added, "In the midst of the heaviest travel period of the year, it is irresponsible that the Senate has left this post unfilled."