If the majority party in the house is the democratic party, it means that the minority is

Republicans is one of the two parties, that exist as minority apart from democratic party in the house.

Explanation:

Republicans is referred as one of the major contemporary parties that is also known as GOP or Grand old party. this party represents an organisation of national committee and is also responsible for development and promotion of republic political platform. it supports those foundations that are concerned with fiscal policies or low taxes.