Sens. Jon Kyl, R-Ariz., and Jim Webb, D-Va., both announced that they will not run for reelection in 2012, thus leaving their seat open.
Kyl has served as senator since 1995, for a total for three terms. Webb will be stepping down after only fulfilling one term following a 2006 election.
Both open seats will leave the incumbent party scrambling for a replacement while the opposition will look to take advantage.
CNN reports that Rep. Jeff Blake, R-Ariz., is a leading candidate to run for Kyl's seat. Kyl also serves as Senate Minority Whip, the position of assistant Republican leader - a position that will be fill by an already-elected member of the Senate.
Democratic leaders hoped that Webb would run again in a state that they were feeling insecure about, according to the Washington Post, especially following Virginia's recent gubernatorial and congressional elections that went for Republicans. Republican George Allen, Webb's opposition in 2006, is expected to contend for the seat for the GOP.
Both cited an interest to move past politics in their reasoning for not seeking reelection. Kyl said he had a pretty clear idea he would not run following his 2006 victory, reported CNN; Webb wanted to explore possibilities in the private sector, according to the Washington Post.
The 2012 Senate election will coincide with the presidential election as well.