Egypt’s largest opposition bloc said Tuesday that it will boycott the country’s upcoming parliamentary elections, heightening the prospect of future instability after months of political crisis and damaging the credibility of the country’s fledgling democracy.

The National Salvation Front, a loose coalition of liberal and leftist political parties, said that it will boycott the late April vote because the Islamist government of President Mohamed Morsi did not consult it in passing a new electoral law and disregarded pressure from the group for, among other things, a new cabinet and a redrafting of the country’s constitution.

“The NSF has decided to boycott the upcoming parliamentary elections because we were not consulted about the election law, and also because all our demands have been ignored,” said Khaled Dawoud, a spokesman for the Front, at a Cairo news conference.

Months of intermittent protests and street clashes have left Egypt’s political forces polarized and have widened the tide of opposition to Morsi, Egypt’s first democratically elected president, and his Islamist backers in the Muslim Brotherhood.

But political analysts and opposition leaders have speculated that the liberals’ chances of making significant gains at the ballot box were already slim; opposition leaders have been unable to overcome deep internal divisions over policies and goals or remedy poor organization.

Without the liberals on the ballot, analysts said, Islamists from Morsi’s Muslim Brotherhood and more hard-line Salafist political parties will sweep the elections. Opposition leaders contend that the boycott highlights a lack of credibility that they say already threatens to undermine the process.

But analysts said the boycott also represents a plea for solidarity on the part of Egypt’s powerful military and its allies in Washington and Europe, who are likely to be uncomfortable with an Islamist-dominated government and parliament in this strategically significant Arab state.

“I think a game is at play here, and the United States, the military and the internal public opinion are a part of it,” said Hazem Hosni, a professor of politics at Cairo University. “I think the NSF’s decision will put great pressure on the regime. . . . If this message reaches the United States, I think it might change a lot.”

The State Department urged Egypt’s opposition on Tuesday to reconsider its decision. Spokesman Edgar Vasquez said it is “critical” for Egyptian parties to participate in the vote so that Egyptians can select from a range of political positions, the Associated Press reported.

Not all opponents of Morsi’s government greeted the boycott with approval. “Ironic that #NSF have boycotted: re-districting for party lists could actually HELP smaller parties, if they play it right,” wrote Hafsa Halawa, an Egyptian who works in democracy promotion, on Twitter.

The NSF also rejected an invitation to participate in a national dialogue convened by Morsi on Tuesday evening. Islamist parties did attend.