Northern Ireland's power-sharing government has been plunged into crisis as the senior Catholic leader says he's resigning amid deepening tensions with his Protestant colleague.

Martin McGuinness says in a statement Monday that he's quitting as deputy first minister of Northern Ireland's unity government at 5 p.m. (1700 GMT).

McGuinness says in a letter to the Northern Ireland Assembly that Sinn Fein intends to trigger early elections.

The government, formed in 2007 under terms of Northern Ireland's peace accord, requires support from Sinn Fein and the major Protestant-backed party, the Democratic Unionists, to survive.

McGuinness has repeatedly called on his colleague atop the government, Democratic Unionist leader Arlene Foster, to step aside from her role while lawmakers investigate her alleged mismanagement of a government "green energy" program that wasted taxpayers' money.