Seldom have America's mid-term elections been watched so closely across the globe.

The reasons are clear enough: what impact they'll have on the competitive attractiveness of US democracy around the world, what clues they will provide about the durability of the Trump administration and its foreign policies and – hardest to calculate --the impact they will have on populist and nationalist momentum globally.

On the first issue regarding US democracy, allies are worried that the American model is losing traction, prompting Chinese leaders to promote their state capitalist model as a viable alternative for developing and developed countries alike.

As Stephen Hadley, former national security advisor to President George W. Bush, recently said to CNN's Fareed Zakaria, "If you're worried about the United States, we have a lot of tools to run a successful foreign policy that is in our interests and can provide prosperity and security for our people. But our brand is not doing well internationally. There's a reason why people are taking seriously China's claim to have a new model. It's because ours doesn't look very good."

During the Cold War, Soviet officials failed over time in making a credible argument that their Communist system could deliver social and economic progress. However, the more that US politics is mired in polarization and the less effective it appears in addressing core problems, the more attractive authoritarian models will appear.