The simpler explanation is that Tom Steyer, as well as the liberal donors and climate activists allied with him, is getting his way. They were always an influential constituency in the Democratic party, but became even more so a few months ago when Steyer pledged $50 million of his own money to Democrats in the midterms, to be matched by another $50 million from other donors. In a punishing year for Democrats, this was rare good news. Why mess it up by deciding Keystone on the merits?
For all the complaints about money in politics, it is unusual that a high-profile decision seems to have such a direct connection to one big-time donor. This isn’t sneaking a small but consequential provision into a 1,000-page bill in the dead of night. It is blocking a project in broad daylight that is important to a close ally (Canada), that will instantly create thousands of construction jobs, that will send a signal to Vladimir Putin that we are serious about developing energy resources, and that will have no net effect on global warming (as the latest State Department review established).
Steyer deserves perverse credit for his success defying what would otherwise be uncontroversial public policy.