Well that is simple. According to John Boehner, Mitch McConnell, Eric Cantor, et al, extending these tax cuts for the richest Americans will allow said richest Americans to create jobs. The part they haven't explained is why these richest Americans have been holding off creating jobs while these tax cuts have been in place...
If you'd pay attention to the business community you'd know that it has been explained over and over and over. Businesses have been erring on the side of caution because they don't know what's going to happen with the tax code. The Congress has been fighting about it all year. Will the tax rates be continued or will they be raised? They also don't know the full effect of ObamaCare and what that is going to do to the bottom line. If the current tax rates are extended, unemployment will go down. Case and point, meet the CEO of Bank of America:
Bank of America's Moynihan: Tax Cuts Could Spur Hiring - MarketBeat - WSJ
As far as manufacturing? The unions killed the manufacturing jobs. Period. No amount of government involvement can mitigate the sort of pay the unions demanded.
Manufacturing in the USA is a thing of the past and those who keep hanging on to the idea that it will some day come back need a kick in the ass. When China and Vietnam and third world nations can do the same work for pennies on the dollar, that's where the production is going to be.