Without a quorum, the Supreme Court ruled last year, the board cannot decide cases.
Republicans on the committee boycotted a vote scheduled for last week, leaving Democrats without a quorum.
And the Texas Senate voted -- without a quorum -- to fine each of them $57,000 for being absent.
A Senate committee recently approved three new members for the Federal Election Commission, which had been without a quorum for months.
The N.L.R.B. is supposed to have five members, and it cannot act without a quorum of three.
That long-simmering problem led to a big embarrassment last week when financial and personal conflicts affecting four Supreme Court justices left the court without a quorum.
They contend that the panel's leadership, seeking to halt the debate on the Boy Scout issue, pushed through a resolution in April without a quorum.
Similarly, without a quorum, the board could not rule on a long-awaited case on whether graduate teaching assistants at private universities have the right to unionize.
The agency, which monitors compliance of federal election laws, has had only two commissioners out of a normal complement of six for months, leaving it without a quorum and powerless to act.
WASHINGTON — Financial and personal conflicts of interest affecting four Supreme Court justices left the court without a quorum last week and unable to decide whether to hear an appeal brought by more than 50 companies that did business in apartheid-era South Africa.
And last week, the N.L.R.B. temporarily suspended putting in place its new election rules soon after a federal district judge found that the board had improperly adopted those rules without a quorum.
