As the debate over Hagel’s likely appointment and foreign policy views continues, I have been struck by a few things that distinguish it from most arguments over presidential appointments: 1) the purely ideological nature of the opposition to his appointment; 2) the diminished effect of bipartisanship as a result of ideological differences between Hagel and Republican hard-liners; 3) the related fact that almost all of the opposition to the appointment is coming from Hagel’s party rather than from unhappy activists in the president’s party; 4) the reality that a Romney administration would never have considered Hagel for this position at all.

While ideology is always a factor in support for and opposition to a given Cabinet appointment, I cannot recall a recent instance when a possible presidential appointment was subjected to so much criticism on what appears to be purely ideological grounds. Many Republican hawks are treating Hagel’s likely nomination the way that some activist groups would treat a Supreme Court nomination or a vice presidential selection. All of the opposition to Hagel so far comes from people who object to him because of what he thinks and what he has said. So far, no one seems to be making the argument that Hagel would be a poor fit at the Pentagon or that he would do a poor job running the department. On the contrary, the hawkish fear and his supporters’ hope are the same, namely that he would be only too effective in making some meaningful changes on military spending and the administration’s willingness to wage unnecessary wars.

Another difference is that appointing a member of the other party is not having the normal desired effect of blunting partisan criticism. Because Hagel has been all but expelled by his party on ideological grounds, the goodwill that such a show of bipartisanship normally buys is conspicuous by its absence. Normally, the possibility of appointing a member of the other party to a top Cabinet post would earn praise even from the administration’s critics, but in this case it is perceived as a challenge and even as an insult. Despite the fact that at least one of Bush’s top Cabinet nominees was directly responsible for contributing to an enormous policy blunder in Iraq, resistance to his second-term appointments was extremely mild and weak by comparison. Assuming Hagel is indeed nominated and goes on to be confirmed, the campaign against him is an unusual response to a possible appointment in a second-term administration.

If there is dissatisfaction with a Democratic appointment of a Republican to a top Cabinet post, it normally comes from strong Democratic partisans and progressive activists. While there have been some complaints from Democrats along these lines, the objections have not been very strong, and there’s no question of significant opposition to Hagel’s nomination from Senate Democrats because of his party affiliation or his views on matters unrelated to national security. Instead, all of the real opposition to his nomination is coming from Republican hard-liners. As they see it, the possibility that he could appoint Hagel isn’t evidence that Obama is firmly within the bipartisan foreign policy consensus, but instead they take it as confirmation that Obama has finally “revealed” the opposite. It’s possible that we would have seen all of this in reverse had Romney won and decided to appoint, say, Joe Lieberman to a top Cabinet post, but as far as I can recall there hasn’t been a debate over a Cabinet appointment quite like this.

Speaking of Romney, the other extraordinary thing about the debate over Hagel is that it’s impossible to imagine Romney appointing him to a similarly important position. When a president considers a member of the other party for a top position, he normally chooses someone broadly acceptable to others in that party, so that it’s easy to imagine the same person filling the same role no matter the party in control of the White House. Hagel is far more in agreement with Obama than he is with Romney’s stated views on foreign policy, and Romney campaigned as the embodiment of everything that Hagel came to dislike about the prevailing foreign policy views inside the GOP. Not only would Romney not have wanted to risk the ire of his hawkish backers, but it would never have occurred to him to consider someone like Hagel. The fact that Hagel would presumably never have even made Romney’s list of possible nominees is one more piece of evidence contradicting the wishful thinking that Romney would have been anything other than a hawkish hard-liner once in office.