The nation's top Democrats are paying attention to Dracut farmer and Republican candidate for Congress, Jim Ogonowski. On Sunday, House Speaker Nancy Pelosi hosted a fundraiser for Niki Tsongas, the Democrat running against Ogonowski, in the race to represent the Fifth Congressional district. The seat opened when Democrat Martin T. Meehan stepped down to become chancellor of the University of Massachusetts at Lowell. A special election is scheduled for Oct. 16.