Salisbury's MP is predicted to lose his seat at the coming General Election according to online analysts.
The Electoral Calculus website is forecasting that the Paymaster General will be beaten by Labour's Matt Aldridge.
Mr Glen was first elected to Parliament for Salisbury in 2010. It comes as a number of polls show the Conservatives could lose up to 18 cabinet ministers including Grant Schapps and Penny Mordaunt.
Labour's Matt Aldridge's candidacy was announced last month. Mr Aldridge, a 'clean air strategist', was previously Head Boy at Bishop Wordsworth’s School.
Electoral Calculus suggests Labour has a 67% chance of winning in Salisbury, with the Tories retaining only 90 of their 348 seats currently held.
The General Election is expected to be held in November, with January 28th next year as the last possible date.