CAIRO – Egypt's main opposition alliance called for a "No" vote in the referendum on a disputed constitution rather than a boycott, hours after Islamist President Mohammed Morsi's government forged ahead by starting overseas voting in diplomatic missions for expatriates.

The opposition's decision did not dispel the atmosphere of a nation in crisis, deeply polarized over the referendum that has stoked three weeks of turmoil on the streets. The opposition still plans more protests and the country's judges still are on strike over a decree by Morsi, since rescinded, that placed him above judicial oversight. The military is inching back into politics. And if the referendum passes, there is potential for even greater upheaval.

There also are growing concerns about the already flailing economy Egypt on Tuesday requested a postponement of a $4.8 billion IMF loan after Morsi, fearing a popular backlash at a time of already heightened tensions, suspended a package of tax hikes that had been part of a program to reduce the huge budget deficit.