JUNEAU, Alaska (AP) – Republican Sen. Lisa Murkowski faces a familiar opponent in her latest re-election bid: Joe Miller, who challenged the Alaska senator six years ago in a historic, roller-coaster race.

Miller, then a political novice, upset Murkowski in the 2010 primary only to see her win the general election with a longshot write-in campaign. It was the first time a U.S. senator had won as a write-in candidate since 1954.

This year’s race has been less dramatic, with recent polls showing Murkowski with a big lead over a crowded field. A number of political observers consider her the over...