Virtually ensures the Muslim Brotherhood will clean up during the upcoming elections.

CAIRO — Egyptian voters overwhelmingly approved a referendum on constitutional changes on Sunday that will usher in rapid elections, with the results underscoring the strength of established political organizations, particularly the Muslim Brotherhood, and the weakness of emerging liberal groups.

More than 14.1 million voters, or 77.2 percent, approved the constitutional amendments; 4 million, or 22.8 percent, voted against them. The turnout of 41 percent among the 45 million eligible voters broke all records for recent elections, according to the Egyptian government.

The Muslim Brotherhood and remnant elements of the National Democratic Party, which dominated Egyptian politics for decades, were the main supporters of the referendum. They argued that the election timetable would ensure a swift return to civilian rule.

Members of the liberal wing of Egyptian politics mostly opposed the measure, saying that they lacked time to form effective political organizations. They said early elections would benefit the Brotherhood and the old governing party, which they warned would seek to write a constitution that centralizes power, much like the old one.