U.S. President Barack Obama has decided to nominate Sen. John Kerry to be the next secretary of state and could make a formal announcement as early as next week, a Democrat who spoke to Kerry told CNN Saturday. The expected nomination follows U.N. Ambassador Susan Rice's decision to withdraw her name from consideration for the post. If confirmed by the Senate, Kerry would replace current Secretary of State Hillary Clinton, who plans to leave her post within the administration. Kerry, the senior senator from Massachusetts and the Democratic Party's 2004 presidential nominee, is noted for the experience, gravitas and relationship-building skills.