During his two terms as a Republican senator from Nebraska, Chuck Hagel certainly distinguished himself as an outspoken, independent thinker. Instead of relying on partisan talking points and toeing the GOP line on controversial issues, Hagel spoke his mind and voted his conscience.

That’s coming back to bite him now that President Barack Obama has nominated Hagel to replace Leon Panetta as secretary of defense. Hagel’s GOP critics are questioning his commitment to Israel and remarks he made advocating diplomacy with Iran. Some Democrats still are stinging over a 1998 statement challenging the nomination for U.S. ambassador to Luxembourg of a man Hagel described as “openly, aggressively gay.”

There’s no question that Hagel, a Vietnam veteran, has a controversial past — all of which is worthy fodder for Senate scrutiny. But, ultimately, the Senate should honor the president’s prerogative to select his own Cabinet members. Regardless of which party controls the White House, it’s the president’s privilege to set policy and appoint those whom he wants to execute it.

Unless the confirmation process turns up glaring evidence of impropriety by Hagel or some other clear disqualifier, this choice is Obama’s to make.

Republicans no doubt are looking for wedge issues to recover lost political ground after the November elections and recent battle over the fiscal cliff. Their concerns forced U.N. Ambassador Susan Rice to withdraw from consideration as secretary of state. In that case, the challenge involved Rice’s job as an administration representative on foreign affairs.

In Hagel’s case, the criticism focuses largely on his past positions on nondefense issues. Although the Pentagon chief’s job does have a large foreign affairs component, the secretary does not set foreign policy. So far, there is no evidence to suggest that Hagel, as a Cabinet member, would stray from administration foreign policy just because he was outspoken long ago.

On defense, Hagel is forceful about restraining Pentagon spending and demonstrably cautious about boosting U.S. military involvement abroad. He is no hawk. Every foreign military engagement entails costs and risks, and Hagel can be expected to warn of consequences should the United States decide to ramp up any military confrontation with Iran.

Perhaps such vocal expressions of restraint rankle those who favor greater adventurism and confrontation, especially as Iran edges closer to obtaining nuclear bomb-making capability. Far worse would be a nominee who advocates deploying troops, shooting first and asking questions later.

Scrutiny is the Senate’s job in the confirmation process, and the Obama administration should embrace it as an important facet of our democracy. But senators must enter the process open-minded and committed to giving Hagel the fair hearing he deserves.