Hundreds of undocumented migrants at a detention centre in Washington state have started a hunger strike, according to supporters, in the run-up to rallies and civil disobedience aimed at forcing through immigration reform.

Detainees at the Tacoma facility started refusing food on Wednesday in a planned 75-hour fast, timed to end on Saturday when activists will march on the White House to demand that President Obama break the reform logjam.

In addition to executive action to halt deportations and bypass Congress, where House Republicans have stalled legislation, the activists are demanding that the president personally meet undocumented leaders, a request which has divided mainstream immigration advocacy groups.

“We’re gathering people from across the nation to pressure Obama. And when there are negotiations, we want to make sure that we have a seat at the table,” Maru Mora Villalpando, a director of Latino Advocacy, told the Guardian.

In Tacoma, a detention centre outside Seattle which has been the scene of repeated protests at conditions and immigration policy, at least 10 pods, each containing 55 to 85 people, are refusing food, said Villalpando. Authorities officially recognise a hunger strike only after 72 hours, hence the 75-hour fast.

Activists from #Not1More, a coalition which uses opposition to deportations to push for wider reform, are hosting small protests in Washington DC in the run-up to Saturday’s march, which they hope will help keep immigration on the political agenda while Obama and Congress head off for summer breaks.

On Wednesday, Villalpando and five others occupied the Capitol Hill office of Mark Takano, a California Democrat who is part of Congress’s LGBT equality caucus. In another act of civil disobedience dozens of activists are due to kneel and pray in front of the White House on Thursday, said Jolinda Stephens, who flew to the capital from Seattle.

In a twist to the immigration reform campaign, some grassroots activists are now pressuring Washington-based advocacy groups to not meet Obama unless undocumented individuals are also invited, reflecting a perception that those inside the beltway have to an extent been coopted.

“We think President Obama is trying to divide our movement. We’re saying they’ve done a great job but to do a perfect job we need to be there too,” said Villalpando, a Seattle-based mother who is herself undocumented.

On Monday activists picketed the White House chanting “no more meetings about us, without us,” and carried homemade signs saying “I am my own best advocate”.

They also visited the Washington offices of the Leadership Conference for Civil and Human Rights, the Center for American Progress and the National Immigration Forum to make their case for inclusion.

The three groups gave no indication they would boycott White House meetings but Marshall Fitz, director of immigration policy at the Center for American Progress, told the Huffington Post the activists had a legitimate request and should be heard directly by Obama. “I cannot make that pledge on behalf of CAP, but I told them that I would urge the administration to engage them directly.”