WASHINGTON (MarketWatch) -- House Majority Leader Eric Cantor told reporters Tuesday that he does not support the Senate-approved fiscal cliff deal. Cantor's defection was the latest and clearest sign that the agreement reached between President Barack Obama and Senate leaders faces an uncertain fate in the House. Alarmed by the Republican opposition, House Democrats have called for a straight up-or-down vote on the measure. House Republicans were talking openly about amending the legislation and sending it back to the Senate for action. This could imperil the measure.