WASHINGTON — Tagged as a bunch of do-nothings, Congress went home this week to face many of winter’s potholes still gaping in July, and local officials panicked that the flow of federal transportation money will begin to dry up within weeks.

This time, House and Senate members will have little choice but to act when they return from the July 4 recess next week. The consequences of doing nothing seem too extreme for all but the most dire obstructionists to endure.

Letters warning that federal funding would begin to dry up Aug. 1 went to state officials this week, foreshadowing a period when money for bridge and highway projects may slow dramatically at the height of the construction season.

Some states, fearful that Congress will fail them, already are planning cutbacks that may put tens of thousands of construction workers out of work. Arkansas, which counts on Washington for 70 percent of its road construction dollars, shelved 14 projects slated for this summer with a price of $70 million to $80 million.

“We see this as a very real threat,” said Randy Ort of the Arkansas State Highway and Transportation Department. “I think some states are gambling that it’s not going to happen.”

IMPENDING CRISIS

Most states get about half their transportation money from Washington. U.S. Transportation Secretary Anthony Foxx, who wrote his second letter in as many weeks to states warning of an impending crisis, said on average states would lose about 28 percent of their federal money.

The issue is one Congress has ducked for several years. Federal transportation dollars come from a dedicated source, the Highway Trust Fund. The vast majority of the fund’s money comes from the 18.4-cents-per-gallon federal gas tax that last was raised 1n 1993. The tax hasn’t kept up with inflation and, largely because vehicles are getting more miles per gallon, the fund has been shrinking and will be unable to pay its bills as soon as next month.

There is general awareness on Capital Hill that shutting down construction jobs and tossing tens of thousands of people out of work in the next few months is seen as bad policy and perilous to the economy.

But the pending demise of the trust fund has been forecast for years without spurring Congress to act to replenish it.