WASHINGTON/PHILADELPHIA (Reuters) – Federal Reserve Chair Janet Yellen has the evidence of U.S. labor market health she wanted in order to raise benchmark interest rates for the first time in a decade this month, but she may have a tougher time selling further hikes. Yellen’s arguments against potential dissenters at the Dec. 15-16 Fed policy meeting were strengthened by Labor Department data on Friday that showed employers hired 211,000 people in November while even greater numbers joined the workforce.