MOSCOW (AP) — Russia’s presidential election campaign formally lasts only three months, and President Vladimir Putin wants to make it as short as possible. With Putin’s approval rating topping 80 percent, there is little doubt about the outcome of the March 18 vote. Instead, voter apathy represents the main challenge for his strategists, who want his showing to be as strong as ever to demonstrate that public support for Putin hasn’t waned 18 years after his first election. In an apparent bid to drum up interest and make a bland race as short as possible to keep voters mobilized, the 65-year-old president waited until last week to declare his intent to run again. It’s not clear yet how Putin will focus his campaign, which was formally opened Friday by the upper house of parliament. Ahead of the 2012 vote, he ran a highly polarizing campaign amid a wave of massive demonstrations in Moscow against his rule.