Mr Bayh was on Barack Obama’s shortlist of vice-presidential candidates in the 2008 race and has never lost an election.  His departure means his seat is now likely to fall to a Republican, further eroding the Democratic majority in the Senate. It also casts a shadow on the Obama administration’s pledges to make Washington less ­partisan.

“I love working for the people of Indiana, I love helping our citizens make the most of their lives, but I do not love Congress,” Mr Bayh said at a press conference in Indianapolis, referring to the partisan bickering that has scuppered Democratic efforts to establish a deficit commission and pass jobs legislation.

Read more here: Bayh’s withdrawal deals blow to Democrats