Former Liberal Democrat MP Lembit Opik described the South Shields result as "appalling" and demanded a "credible explanation from Nick Clegg regarding the recovery strategy".
The Lib Dems secured just 352 votes.
Mr Opik lost his Montgomeryshire seat in 2010.
.@davidlhennigan fair point but let's be honest: appalling result. Veteran members deserve to know how this electoral crisis will be fixed
South Shields by-election gave 1.4% for Lib Dems. I ask for a credible explanation from Nick Clegg regarding the recovery strategy.
More top news
Thicker cloud across Ireland and northern Scotland but otherwise a very pleasant afternoon.
On the day of the race, the fundraising website went down due to a rush of last-minute donors.
The device was found outside the gates of Holy Cross Boys' Primary School in Belfast.