Former business secretary Vince Cable is the first candidate to enter the Lib Dem leadership race following Tim Farron's decision to step down last week.
Cable currently served as the party's Treasury spokesman, and made the announcement on the Lib Dem Voice blog.
At 74, Cable is the senior statesman among the party's MPs. He has previously served as Lib Dem deputy leader and interim leader while members selected Nick Clegg in 2007.
Securing the leadership of his party would complete a remarkable return for Cable, who was rejected by voters in 2015 only to win his Twickenham seat back earlier this month.
It comes after bookies favourite and former minister Jo Swinson ruled herself out of the running, stating instead she will seek to become deputy leader.
Tom Brake, currently serving as Lib Dem spokesman for Brexit and international trade, has suggested he is also unlikely to run, while former energy secretary Ed Davey is among the MPs considering throwing his hat into the ring.
Farron quit the leadership in the aftermath of the General Election. Although the Lib Dems gained seats earlier this month, the party's vote share also decreased, while Farron faced repeated questions over his religious views.