The DUP give the Tories a working majority of 13.
Are the DUP at liberty to withdraw support for any reason?
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Sign up to join this communityTheir agreement with the Conservative party spells this out plainly:
Duration of agreement
The agreement reached will remain in place for the length of the Parliament, and can be reviewed by the mutual consent of both parties. [...]
In this context, "the length of the Parliament" appears to mean "until the next election." Under the Fixed Term Parliaments Act, the next election will be held no later than 5 May 2022. The agreement specifically is not tied to Theresa May; if the Conservatives replace her as PM, the DUP will still be bound. Also, the parties can reopen negotiations at any time by mutual consent (for example, if they decide that the Irish border question needs to be more specifically discussed).