WASHINGTON — President Barack Obama's pick of Chuck Hagel to run the Pentagon faces rough going in the Senate as a handful of Republicans quickly announced their opposition to a former GOP colleague, and several skeptical Democrats reserved judgment until the nominee explains his views on Israel and Iran.

The concerns about Hagel complicate his path to Senate confirmation but are not necessarily calamitous as the White House pushes for the first Vietnam War veteran to oversee a military emerging from two wars and staring at deep budget cuts.

Obama also tapped White House counterterrorism adviser John Brennan to head the CIA. Brennan, a 25-year CIA veteran, faces no major obstacles, but he is expected to be hit with questions about torture and administration leaks of secret information.