Under withering attack from Republicans and facing a potential boycott by one of its members, the National Labor Relations Board is set to vote Wednesday on a rule that would dramatically shorten the time between when a union is proposed and when employees hold an election to join.

It's called the “microwave” rule, and by allowing workers to form unions more quickly, it would give employers less time to take legal action – or other steps – to block the move.

The vote puts the NLRB in controversial waters for the second time this year. The board infuriated Republicans earlier this year when it alleged that Boeing moved part of its Dreamliner assembly line to South Carolina – a right-to-work state – in retaliation for union activity at its main plant in Washington State.

It also comes at a time when unions are trying to fend off attacks from Republicans in Congress and in statehouses.

In several states, including New Hampshire and Indiana, conservative lawmakers are trying to curtail labor rights as a strategy for controlling state budgets and encouraging economic growth. Wisconsin has already passed such a bill, leading to a national backlash and state recall elections.

In Washington, D.C., meanwhile, Republicans say the Obama administration is proposing job-killing initiatives amid stubborn, near-double digit unemployment. Supporters of President Obama say he is attempting to protect already-dwindling worker rights from corporate hegemony. Below the surface is a political tug of war over the influence of organized labor in politics – particularly union financial support of Democrats ahead of next year's election.

"The stakes are relatively small [in this vote], which indicates that the real battles have been displaced by symbolic battles,” says Colin Gordon, a labor historian at the University of Iowa in Iowa City. “That's not to belittle the importance of federal labor law, however. It would make a big difference if we had a larger overhaul that would allow, for example, microwave organizing and allow different forms of union organizing.”

Congressional Republicans decry what they see as the White House using its executive power – through the NLRB – to circumvent Congress. The microwave rule proposes to reduce the time between when workers file to form a union and when they vote from 30 days to as few as 10.

“What the NLRB is doing is not the action of one rogue agency or a few envelope-pushing employees, so much as it is a deliberate strategy to use the federal government's regulatory powers to achieve what Obama and his political supporters want without having to bother with going to Congress first,” writes columnist Peter Roff for US News and World Report.

The pro-union actions of the NLRB stand in contrast to more sweeping battles in the states, where emboldened Republicans have proposed a growing number of anti-union reforms in the past two years. The legislation includes attempts to limit automatic union-dues deductions from paychecks and to curtail collective-bargaining rights for public employees.

In New Hampshire on Wednesday, state Republicans said they will attempt to overturn a gubernatorial veto of a law that would have made the Granite State the 23rd right-to-work state in the US. In right-to-work states, workers do not have to pay a fee to unions if they choose not to join, significantly undercutting union clout. Indiana Republicans say they plan to introduce bills next year to turn Indiana into a right-to-work state, as well.

Those moves come despite a petition to recall Gov. Scott Walker (R) of Wisconsin for his role in pushing a bill that stripped many state public unions of their collective-bargaining rights. And earlier this month in Ohio, voters repealed a similar anti-union law that prohibited, among other things, workers from striking.

The NLRB vote on microwave unionizing is one check on the broader national attack on organized labor, union leaders say. “These are modest but important reforms to help ensure that workers who want to vote to form a union at their workplace get a fair opportunity to do so,” AFL-CIO spokesman Josh Goldstein told Bloomberg News. “We hope the board will adopt these measures tomorrow and quickly move to adopt the rest of its proposed reforms.”

The issue is expected to come to a head Wednesday. The five-seat NLRB currently has only three members – two Obama appointees and a Republican. The two Obama-appointed members were appointed during congressional recesses, while two other Obama appointees for the remaining open seats have yet to be confirmed by the Senate.

If the NLRB approves the microwave provision, House Republicans say they'll pass a bill gutting it.

“Let’s be blunt here,” Republican Rep. John Kline of Minnesota said in a call with reporters Tuesday. “Elections have consequences. This is President Obama’s board, and he’s supporting this. If he’s not going to step in and put some reins on the board, we in Congress have to do everything we can to.”

But previous House bills to defund the NLRB and oppose its efforts against Boeing have gone nowhere in the Democrat-controlled Senate.

The NLRB's lone Republican, Brian Hayes, has threatened simply not to attend the meeting, which could mean the board wouldn't have a required quorum. In response, NLRB Chairman Mark Gaston Pearce said Wednesday morning that the rule could be modified so it would only affect organizing efforts that were held up by “needless litigation.”