Sterling fell on Friday and was headed for a third consecutive week of losses as caution grew among investors about the British parliament's vote on Brexit next month.
Prime Minister Theresa May said on Thursday she was focussed on persuading MPs to back her divorce deal with the European Union in a Dec. 11 vote, rather than preparing a plan B.
May secured an agreement with EU leaders on Sunday that will see Britain leave the bloc in March next year with continued close trade ties, but the odds look stacked against her getting it through a deeply divided British parliament.
Those concerns were reflected in the currency markets, with the British currency down nearly 3 percent in the last three weeks and derivative markets indicating more hedging activity before the vote.
The pound at 15:50 GMT was down 0.3 percent at $1.2756 against a resurgent dollar. Against the euro, it was also down 0.3 percent at 88.24 pence.