Pro-Moscow lawmakers made the request to Russian President Vladimir Putin and said they would put the question to a referendum on March 16 as Russian forces maintained their grip on the strategic Black Sea peninsula.
The referendum, which was brought forward from a planned March 30 date, will also ask if residents want to a return to a previous 1992 constitution that gave the region sweeping autonomy.
Tensions ran high on the rugged peninsula, where military observers from the Organization for Security and Co-operation in Europe were set to begin a monitoring mission later today.
The majority Russian-speaking Crimea has been embroiled in crisis.
The 40 monitors from 21 OSCE countries were invited by Ukraine, which is in a standoff with local authorities after a Kiev court ordered the arrest of Crimean leader Sergiy Aksyonov for separatism.
"It's extremely tense and I consider it a miracle that bloodshed has been avoided so far," Tim Guldimann, personal envoy of the Swiss chair of the OSCE, said in Kiev after returning from Crimea.
"Apart from the presence of these military personnel, a very dangerous aspect is the build-up of self defence militias who are armed," he said.
Guldimann said he cut short his visit after UN special envoy to Crimea Robert Serry was forced to leave yesterday after being confronted by gunmen who said they had orders to take him to the airport.
The majority Russian-speaking Crimea has been embroiled in crisis for over a week, following the ouster of Ukraine's pro-Moscow president Viktor Yanukovych.
Russian forces on the territory, home to Kremlin's Black Sea Fleet, have surrounded Ukrainian military bases for days and on Thursday also scuttled an old warship at the entrance of a lake, trapping Ukrainian vessels.
Inside the Ukrainian bases, nervous soldiers were standing their ground, refusing to surrender or hand over their weapons, but in most cases clearly not ready to hold off a full-out Russian assault.