NEW YORK, March 13 (Xinhua) -- Major U.S. airports are seeing long lines at security checkpoints amid an ongoing partial government shutdown that has dragged on for nearly a month.

About 50,000 Transportation Security Administration (TSA) officers have been working without pay since Feb. 14, when the U.S. Congress let funding for the Department of Homeland Security, which oversees the TSA, expire over a disagreement on immigration enforcement.

Travelers faced waiting time of up to more than three hours at airports in New Orleans and Houston over the weekend.

Photos and videos online showed lines at Austin-Bergstrom International Airport stretching from the terminal building into the parking lot.

In the New York City area, delays at John F. Kennedy International Airport, LaGuardia Airport and Newark Liberty International Airport stretched nearly an hour. Terminal C at Philadelphia International Airport was temporarily closed on Thursday to ease the strain on staff.

Experts warned that things could worsen this weekend as U.S. citizens travel for spring break, and TSA agents were set to miss their first full paycheck on Friday, increasing the likelihood they will skip work.

Some airports asked passengers to allow more time than usual to clear security, as staff shortages cause more congestion and longer lines.

As the Senate worked to advance a bill to end the partial government shutdown, both Republicans and Democrats cast blame across party lines for the lengthy shutdown.

According to a travel forecast from Airlines for America, an estimated 171 million people are expected to fly during spring break this year.