(Reuters) - The differences over how to resolve the "fiscal cliff" narrowed significantly Monday night as President Barack Obama made a counter-offer to Republicans that included a major change in position on tax hikes for the wealthy, according to a source familiar with the talks.

The move, which the source stressed was not Obama's final offer, was welcomed, albeit with reservations, by a spokesman for Republican House of Representatives Speaker John Boehner, who met earlier in the day with Obama as the two hammered out a way to avert steep tax hikes and indiscriminate spending reductions set for the beginning of 2013.