The ghost of Jack Kevorkian for President's Physician: 2016
It makes more sense to reduce taxes on those who are most likely to spend the tax savings -- the middle class and the poor (if the intent is to stimulate consumption). Given the blood oath the Republicans have taken to not reduce taxes on the poor without reducing taxes on the rich (who would contribute essentially nothing to consumer demand as a result), reducing payroll taxes is a way to work around Republican intransigence (i.e., since the rich do not pay much in the way of payroll taxes, most of the cut goes to the poor and middle class instead of the rich).
The Republicans do not like the poor and middle class getting a break, while the rich do not, so they are doing everything possible to poison the payroll tax cut extension, or at least extract as much blood from Obama as possible, in the way of attachments such as the XL pipeline. Quite simply the GOP is fueled by hate and greed, which has been supercharged by the Tea Party caucus.
Obama SHALL approve the pipeline UNLESS he finds it NOT IN THE NATIONAL INTEREST. If he finds it not in the national interest, he SHALL file a timely report with various people, some of whom likely hate his guts, EXPLAINING WHY he does not find it in the national interest.
At that point we can safely assume a back-stabbing media campaign will begin, quite possibly including legal action to rule his non-national-interest reasoning null and void, allowing the pipeline project to proceed.
The House bill DOES NOT ALLOW Obama to merely refuse to approve the pipeline "because he doesn't want to".
"The truth shall make you free" -- John 8:32