The Independent Payment Advisory Board, which would become a panel of bureaucrats tasked with holding down Medicare costs, has been a lightning rod of controversy ever since Obamacare was first proposed. It has been derided by both Republicans and Democrats and even fueled part of Obamacare's "death panel" controversies.
One of the primary complaints about IPAB is its unaccountable nature - the bureaucrats would be appointed by the President and its recommendations about health care cuts would be nearly impossible to override by Congress. Even hard-Left Democrats like Barney Frank, Loretta Sanchez and Pete Stark have derided IPAB.
IPAB's mission in cutting Medicare might be nigh-impossible. The board was tasked with cutting costs without touching some very big-spending parts of Medicare, and the savings are going towards big spending in other parts of Obamacare. It's politically toxic (see the number of Democrats supporting its repeal) and would likely fail even in the event it was kept in its current form. It's no wonder it's been targeted for attack.
Even in the event that both the House and Senate pass an IPAB repeal bill, it would have to be with massive amounts of support, because Obama would surely wield his veto pen. Nonetheless, it'd be a minor hit to Obama's popularity, as he'd be forced to support, in a high profile way, one of the most controversial parts of his landmark health care legislation. And one gets the feeling that's what Republicans are going for no matter what.