Ashworth (pictured) is concerned by the recruitment of Laura Wyld - a former member of staff for Conservative Campaign Headquarters - to work in the Prime Minister's Appointments Unit, which supports his role in appointments.
He wrote in his letter that he opposes with Wyld's selection for the job, which is “intended to be politically impartial, and... has responsibility for making public appointments on the basis of merit, not party political allegiance”.
Ashworth asked Heywood whether the post had been publicly advertised with an open recruitment process; who oversaw the process; how many other former Conservative Party employees are now employed in civil service posts; and how many of these were appointed following an open recruitment process.
He also asked for a “full list of all appointments in which the Prime Minister's Appointments Unit has played a role since May 2013”.
A Cabinet Office spokesman said government has not yet received the letter, but that Wyld was appointed on a short-term fixed term contract for one year "by the civil service according to established civil service recruitment processes”.
He added: “She is a civil servant and therefore subject to the full requirements of the Civil Service Code, including political impartiality.”
Under current rules, the Civil Service Commission can grant exemptions from standard recruitment processes for particular posts, allowing appointments to be made without open competition based on merit.