Hello and welcome to the Intelligence on Economist Radio.

I'm your host, Jason Palmer.

Every weekday we provide a fresh perspective on the events shaping your world.

The killing of Iran's military commander, Kasim Salamani,

seemed to foster national unity.

But that tide swiftly turned following Iran's accidental downing of a Ukrainian passenger plane.

We ask what the widespread protests mean for the regime's future.

And public transport in Columbia's capital requires quite a bit of patience.

We take a look at how Bogota's once adored, cheap alternative to a metro system went so wrong.

First up, though.

Tonight, Democratic candidates will take to the stage for their seventh debate.

Unlike previous contests which had up to 20 candidates facing off,

tonight's will feature only six.

The debate comes as primary season is about to get underway.

At long last, people are about to start voting.

John Fasman is our Washington correspondent.

Iowa caucuses on February 3rd, and then after that you have a contest every week for the next two months.

You have Iowa, followed by New Hampshire, followed by Nevada, followed by South Carolina,

followed by 16 states and territories voting on Super Tuesday.

So we are really getting to the point where we're going to stop paying attention to bubbles and start paying attention to results.

The crowded field of candidates is thinning.

Yesterday, Senator Cory Booker was the latest to drop out of the race.

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