get one's foot in the door

Probably from a practice attributed to door-to-door salesmen of placing a foot in the opening of a prospective customer's door, thereby preventing the person from closing the door until the conclusion of the sales pitch.

• "And the legislature had better study Texas, before it commits this state to parimutuel betting, thus letting the professional gambler get his foot in the door."
• "Guinier recognizes the need for minorities to get their feet in the door, but argues that "insiders" must be authentic representatives in order for minorities to achive real political power."
• "But despite his academic credentials, Julian had to fight just to get his foot in the door at most laboratories."
• "He was able to gain employment as a cleaner relatively quickly. It was a 'foot in the door', but it wouldn't appease his ambition for long and he later qualified as a 'passed cleaner' (a fireman in all but name), based at King's Cross and St Pancras."

• have one's foot in the door
• have a foot in the door
• foot-in-the-door technique
• put one's foot in the door