TALLINN, Estonia (AP) — Vladimir Putin is expected to seek another term in the Kremlin when Russia holds presidential elections next March. But he is 71 years old, an age when death or serious illness are hardly distant concerns. If Putin was not on the ballot for some reason, it’s not clear who might take his place. At the national level, Russia’s political system has no primary elections in which voters can choose a candidate. Political parties select their own contenders and then present them to the electorate. However the process plays out, a candidate almost certainly would come from within the current power structure, as none of the lesser parties’ candidates would have wide recognition or support.