CAIRO - Egypt's main opposition coalition said Tuesday that it will boycott upcoming parliamentary elections, a decision likely to push the country into a new round of political turmoil and worsen an already troubled economy.

The announcement by the liberal, secular National Salvation Front was made in a televised news conference just hours ahead of the start of a "national dialogue" convened by Islamist President Mohammed Morsi to produce recommendations on ensuring the "transparency" and "integrity" of the vote. The NSF said it was also boycotting the dialogue.

The decision to boycott the election, to begin in April, is a bid to undermine the legitimacy of the rule of Morsi and the fundamentalist Muslim Brotherhood.

Opponents accuse the Brotherhood of monopolizing power, and the country has been embroiled in protests amid public anger that the Brotherhood has failed to resolve the nation's woes or meet the hopes of the revolution that toppled Hosni Mubarak's authoritarian regime in 2011.

But the opposition also runs a risk. It presented a united front in its decision, but some factions may break ranks to run candidates. There is also no guarantee that the public will rally behind its call to stay away from the polls - making turnout a key measure of support.

The Brotherhood won around 50 percent of the lower house of parliament's seats in elections in the winter of 2011-2012 that were contested by all sides. Other Islamists won another quar-ter of the seats, leaving liberal and secular lawmakers with only a small portion. The chamber was later dissolved by court order.

The United States, Egypt's longtime economic and military benefactor, pressed the opposition to reverse its boycott decision.

State Department spokesman Edgar Vasquez said it is "critical" for Egyp-tian parties to take part so that Egyptians can select representatives from a broad range of political positions. He said the U.S. encourages all parties and potential candidates to compete.

President Obama spoke by phone Tuesday with Morsi, emphasizing the Egyptian leader's "responsibility to protect the democratic principles that the Egyptian people fought so hard to secure" and urging him and others to find consensus, the White House said.

Secretary of State John Kerry is to visit Cairo over the weekend.