The direction of U.S. politics tends to coincide with whatever permanent, national 3rd party does best in presidential elections. From the teens until the sixties, the Socialists did well and then since about 1968 the Libertarians were generally the largest 3rd party. The last two elections have seen Ross Perot's party come in third-- but the jury is still out on how permanent his party will be. After the Perotistas, the Libertarians actually trailed Ralph Nader and the Green Party. I'm hoping that will become the permanent best third party, if not the Labor Party.
For the last 30 years, milder Libertarian ideas have crept into enactment, thru both political parties. I've never expected the Libertarians to last, though, because the ones I've met are too self-centered to sit thru long meetings or to donate generously to their party's treasury.
James in Philly