The clock is ticking for 1.8 million out-of-work Americans who face losing their unemployment assistance at the end of the month, unless Congress votes to extend their benefits. Millions more will lose their benefits in June without an extension.

On Thursday, labor activists will lobby outside Sen. Scott Brown’s Western Mass. office in Springfield to urge him to support extending benefits. Right now, proposed legislation that would extend unemployment eligibility is kicking around Capitol Hill, along with a proposal that would keep in place a pay-roll tax deduction that’s also set to expire on the last day of the year. So far, though, those efforts have stalled. Each major party blames the other for the deadlock.

The national unemployment rate was 8.6 percent in November, down from 9 percent in October. That’s the lowest it’s been since March of 2009. In Massachusetts, the unemployment rate is 7.3 percent; in Springfield, it’s 11 percent.

Thursday’s rally is part of a “National Day of Mobilization for the Unemployed and for Jobs.” Participants will gather outside Browns’ office, at 1550 Main St. in Springfield, at 4 p.m.

“Unless Congress acts, millions of Americans face the prospect of going hungry and getting thrown out of their homes soon after the holidays,” say organizers. “Jobless union members, veterans, students and millions of others are struggling to make ends meet while heartless ‘leaders’ in Congress support the wealthiest 1%. We will send a clear message that America must work for the 99%.”

The AFL-CIO is also organizing a march on the U.S. Capitol that same day.