Prime Buzz: Gov. Kathleen Sebelius vetoed legislation to allow a sizeable coal plant expansion in Western Kansas today. The bill would have eliminated the discretion a state regulator used last year to block Sunflower Electric Power Corp.’s plans to add two coal-burning plants to its existing Holcom, Kan. power station. The long-anticipated veto sets up a showdown with the Legislature, where leaders are counting votes to see whether they have the two-thirds majorities needed to override a …