Why is the US not a democracy, but a constitutional republic?

America is a republic and not a pure democracy. The contemporary efforts to weaken our republican customs and institutions in the name of greater equality thus run against the efforts by America’s Founders to defend our country from the potential excesses of democratic majorities. American republicanism and the ordered liberty it makes possible are grounded in the Federalists’ recognition that non-majoritarian parts of the community make legitimate contributions to the community’s welfare, and that preserving these contributions is the hallmark of political justice. But, the careful balance produced by our mixed republic is threatened by an egalitarianism that undermines the social, familial, religious, and economic distinctions and inequalities that undergird our political liberty. Preserving the republican freedoms we cherish requires tempering egalitarian zeal and moderating the hope for a perfectly just democracy.

The president's only official legislative duty is to sign or veto bills.