Normally it takes even more votes to change any Senate rule (two-thirds, or 67 votes).

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His party does not have the necessary two-thirds majority in the assembly to rule on its own.

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Still, for years afterwards the Republicans were able to wield great influence as a minority party thanks to a rule that required a two-thirds supermajority in both chambers to pass a budget.

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Back in the 1970s the people supporting the mini-bottles-only rule got it embedded in the state constitution, any amendment to which requires a two-thirds vote by both houses of the state legislature, as well as approval by a majority of South Carolina's voters in a referendum.

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But Mr Cash, speaking to the amendment tabled jointly by Labour and a number of Tory backbenchers to remove the need for a two-thirds majority to force an early election, said the rule ran "contrary to all constitutional precedent and history since our parliament first sat".

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For 200 years, the chamber has operated on the understanding that any rule-change requires the vote of two-thirds of its members.

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At the height of its mainframe dominance in the 1980s, the rule of thumb was that IBM accounted for half of industry revenues, two-thirds of the profits and three-quarters of the market cap.

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