Unlike Holder, Lynch is neither a personal friend of the president’s nor someone with a pronounced political profile. Based on her career so far, she seems likely to be more circumspect and self-effacing than Holder, who treated the attorney general’s office as a bully pulpit and wasn’t above lecturing both members of Congress and a U.S. population that he described as “essentially a nation of cowards” when it came to discussing race.
Obama did consider other more provocative candidates, notably Secretary of Labor Tom Perez, a former head of the Justice Department’s Civil Rights Division and a favorite of progressives, and former White House Counsel Kathryn Ruemmler. (Republicans would have been sure to question promoting the promotion of a White House staffer to the AG’s position, though they didn’t object when Ed Meese and Alberto Gonzales made the same migration during Republican administrations.)
It's appropriate for senators to question Lynch about her views about the law, but there are signs that some Republicans want to press her to repudiate Obama policies -- particularly his announced intention to take some sort of executive action to defer the deportation of additional immigrants who are in the country illegally.
Sens. Ted Cruz (R-Texas) and Mike Lee (R-Utah) already have demanded a statement from Lynch about "whether or not she believes the president's executive amnesty plans are constitutional and legal." They implied that, if she were to endorse Obama's plan, that would show she lacked "full and complete commitment to the law."
This is partisan mischief. It's possible that, if confirmed, Lynch might be asked to weigh in on the legality of whatever Obama decides to do, perhaps after a review by lawyers in the Justice Department's Office of Legal Counsel. (That assumes the president doesn't act before the hearings.) But conditioning Lynch's confirmation on her supplying the "right" (i.e., anti-Obama) answer about the legality of a hypothetical executive action would be an abuse of the process.