Bulgaria's ruling GERB party candidate, Rosen Plevneliev, is set to win a presidential election run-off on Sunday with about 55 percent support, two exit polls showed.

An Alpha Research poll showed Plevneliev winning 54.8 percent of votes compared with 45.2 percent for the opposition Socialist candidate Ivailo Kalfin.

A second poll by Gallup International put Plevneliev on 55.3 percent and Kalfin on 44.7 percent.

(Reporting by the Sofia bureau)