The throngs of people called for measures that would allow the estimated 11 million immigrants in the country illegally to attain legal status.
The so-called Gang of Eight senators negotiating language that could pass congressional muster had been expected to reach a deal by the end of the week, ABC News reported, but could be pushed back while gun control legislation takes center stage.
The Citizenship for 11 Million rally drew people such as Mexican immigrant Giselle Stern Hernandez, who held a sign stating she is "a Deported Man's Wife."
"When [my husband's] deportation happened in 2001, people were protesting, but not in the national dialogue the way it is now, so it is deeply emotional for me," Hernandez told ABC. "I'm not putting any hopes on seeing the reform that I would like, but at least these people are engaged in the dialogue.
"We can't just stay in our corners."
The network said a frequent slogan heard and seen at the rally was "The time is now."
"It is time, actually it is past time, for immigration reform for the over 11 million people in this country coming out of the shadows," Emira Woods, co-director of Foreign Policy In Focus at the Institute for Policy Studies and originally from Liberia, told ABC.
"We, all of us, have found family members, community members, church members facing deportation in inhumane conditions and we're here to say, enough is enough."
Washington may have been the focal point of the immigration movement Wednesday, but rallies also were held in many U.S. cities this week, including Staten Island, N.Y.; New Haven, Conn., Charlottesville, Va.; and Boston, ABC said.