Yes, an Affidavit of Support required. As part of the application for your green card your US Citizen spouse must file an Affidavit of Support and prove that s/he is able to financially support you once you get your green card and become a lawful permanent resident of the United States. This is often referred to as Sponsorship, i.e. when filing the Affidavit of Support your US Citizen Spouse is the Sponsor. Your US Citizen spouse’s ability to support you is determined by the Poverty Guidelines (USCIS Form I-864P), which sets the minimum income requirement for use in completing an Affidavit of Support.
The Affidavit of Support is a contract between you, your US Citizen spouse and the US government that allows the US government to sue your US Citizen spouse for reimbursement of money should you, the immigrant, get public benefits from the US government.
The sponsor liability can come to an end when the intending immigrant becomes a US Citizen.