The pound is diving ahead of parliament's crucial Brexit vote

• British pound tumbles against the dollar in the minutes before crucial UK parliament vote on Brexit deal.
• Prime Minister May is widely expected to suffer a crushing, and possibly record-breaking, defeat in the House of Commons.
• Uncertainty over what happens if May loses the vote has helped push the pound down more than 1% against the dollar.
• Follow the pound's movements live at Markets Insider.
• Business Insider has live coverage of the crucial vote, follow it here.

The British pound is diving Tuesday evening as British lawmakers prepare for a historic vote on Prime Minister Theresa May's Brexit deal.

May is widely expected to suffer a crushing, and possibly record-breaking, defeat in the House of Commons, adding even greater uncertainty to the UK political landscape, and increasing the likelihood of Britain staying in the EU, or a general election, or a no deal Brexit.

That uncertainty has pushed the pound significantly lower as of around 7.00 p.m. GMT (2.00 p.m. EST), with the currency trading down more than 1.2% against the dollar, hovering around the $1.27 mark, as the chart below illustrates:

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