MONTGOMERY — State Sen. Rodger Smitherman of Birmingham has been elected president pro tem of the Alabama Senate.

His election came as state Sen. Hinton Mitchem, a Democrat from Union Grove, resigned the position Thursday afternoon. A majority of the Senate elected Smitherman, a Democrat, over Republican Sen. Jabo Waggoner of Vestavia Hills.

The president pro tem is the top spot that a senator can hold.

Democrats in the Senate promised Smitherman in 2007 that they would elect him president pro tem in 2009 if he sided with his own party in organizing the Senate rather than siding with the Republican minority.