Beneath the capital's radar looms a vexing problem — a catchall spending package that's likely to top $1 trillion and could get embroiled in the politics of building Trump's wall at the U.S.-Mexico border and a budget-busting Pentagon request. Despite the big power shift in Washington, the path to success — and averting a shuttering of the government — goes directly through Senate Democrats, whose votes are required to pass the measure. The path for the huge spending measure — by Republicans' own choice a piece of leftover business from last year — would be difficult and complicated in a smoothly running Washington. [...] partisanship has engulfed the city, and the upcoming measure is made even more challenging once upcoming Trump requests for $18 billion or more for the Pentagon and money for his contentious border wall are added to the mix. The administration, however, is off to a slow start, just last Wednesday winning Senate confirmation of its budget director, Mick Mulvaney, who has his hands full with Trump's broader budget submission for the upcoming year as well as plans for the supplemental Pentagon spending or the border wall The most recent one, caused by House Republicans, came as tea party lawmakers insisted on a failed strategy of using shutdown threats as leverage to try to block implementation of Obama's health care law.