No, this isn't necessarily Keynesian: you said you want the GDP to grow. You said that right here:
Okay, so you want to grow the GDP by keeping taxes low. In particular, Mitt Romney endorses lower tax rates than we already have, which can be viewed here at
business insider. So we can "get GDP up" by lowering tax rates (this would be the conservative plan, and the one Romney currently endorses) which would increase the deficit, or we can "Get GDP up" via fiscal stimulus -- which would also increase the deficit.
Whether you're conservative or liberal, "getting GDP up" requires spending through tax cuts, or fiscal stimulus, or both. This is a basic principle of economics; we have scarce resources and no single, particular choice will give us everything we want. Giving a larger percentage of GNI to the poor leaves a smaller percentage for the wealthy; increasing monetary supply increases spending, but also increases inflation; increasing GDP via any means requires deficit spending.
So which do you choose? A higher deficit or a higher GDP? Economics is the study of scarcity, and it tells you that you cannot have both.