Graham Allen (a government whip during Tony Blair's first government) makes the case in "The Last Prime Minister: Being Honest About the UK Presidency" (2003) that the office of prime minister has presidential powers, as did Michael Foley in "The British Presidency" (2000). However the power that a prime minister has over his or her cabinet colleagues is directly proportional to the amount of support that they have with their political parties and this is often related to whether the party considers them to be an electoral asset or liability. Also when a party is divided into factions a prime minister may be forced to include other powerful party members in the Cabinet for party political cohesion. The prime minister's personal power is also curtailed if their party is in a power-sharing arrangement, or a formal coalition with another party (as happened in the coalition government of 2010 to 2015).