EDGARTOWN, Mass. — President Obama said Monday that Iraq had taken a “promising step forward” in forming a more inclusive government even as Prime Minister Nuri Kamal al-Maliki appeared to resist efforts to replace him as the country’s leader.

Speaking briefly to reporters from his vacation home on Martha’s Vineyard, Mr. Obama did not mention Mr. Maliki but pledged his support for Haider al-Abadi, the man chosen to succeed him. And Mr. Obama vowed to step up his support for a new government in its intensifying fight against Sunni militants.

“There will be difficult days ahead,” Mr. Obama said. “We stand ready to partner with Iraq in its fight against these terrorist forces.”