The reason the federal government spends and borrows with no restraint is because of the income tax and the Federal Reserve. The 2nd plank of the Communist Manifesto is the graduated income tax; why does a supposed capitalist country have a Marxist income tax? If we were a truly free market economy, workers would keep their money and government limited by the Constitution.
An even bigger question is: why do no "conservative" leaders advocate ending the income tax? Some of them want to replace it with a different form of tax slavery such as a flat tax or fair tax, but fairly distributing enslavement to the government is still slavery.
The only conservative who proposes to end the income tax is Ron Paul, and he really is a libertarian.