Democratic lawmakers in the Washington region said they will lobby to protect social-service programs that President Obama wants to slash in his $3.7 trillion budget proposal for 2012 even as they fend off efforts by House Republicans to make much deeper budget cuts.

Obama proposed cutting $300 million from the Community Development Block Grant program local governments use to pay for economic-development initiatives in impoverished areas. He also recommended cutting home-heating assistance for low-income residents in half, from $5 billion nationwide to $2.5 billion, and prohibit the use of Pell Grants, which low-income students use to pay for college, for summer courses.