The Republican presidential primary has both a blessing and a curse: a staggeringly deep field of candidates, many of them talented, experienced and/or plausible as national candidates. With four sitting and five former Governors (all but one of them having been re-elected at least once) and four sitting and one former Senators, collectively, they’ve won 34 statewide elections, and served over 220 years in elected office, representing as diverse a collection of states as you could ask: Florida, Ohio, Texas, Virginia, Pennsylvania, New York, Arkansas, Wisconsin, Louisiana, New Jersey, South Carolina, and Kentucky. And that’s before you get to the three political amateur candidates: Donald Trump, Ben Carson, and Carly Fiorina. The opportunities this presents include a field with a surplus of quality candidates that can survive a meltdown by any one of them, and a diversity of views that ought to lead to a genuine debate about the policy direction of the party across a wide array of issues. But it creates problems as well, such as the impracticality of a 17-candidate debate (thus, the latest effort by CNN to bend its rules to squeeze Fiorina onto the main, 11-candidate debate stage), and the fact that such a splintered field makes it hard for candidates without a ton of name recognition to raise money and their poll standing to compete with Trump and Jeb.

In past presidential contests, some early entrants dropped out well before the voting started. There are rational reasons why many of the candidates who are currently doing poorly in the polling should or will stay in the race. And we all have our own preferences of who we would like to see go away. But the candidate who has the least reason to stay in and the most reason to get out of the way immediately and free up some more oxygen for the rest of the field is Lindsey Graham.

I have a chart I use on Twitter to rank the field, and removing my personal preferences for the moment and sorting it by their experience in public office, here it is:

A few of these candidates are clearly doing well enough at present to justify their staying in the race right now, just based on the polls – Trump, Carson, Jeb, Cruz, Rubio, and Walker are the top 6 in the national RCP poll average, plus Kasich is second and in double digits in New Hampshire, and Fiorina is gaining some momentum in all these polls. Jindal is staying in the race through Iowa, gambling everything on a state where he’s spent a lot of time and money. Like a number of the candidates back in the field, he’s learned both the lessons of past winners (usually Democrats like Clinton in 1992 and Carter in 1976) who started as dark horses, and the lesson of Tim Pawlenty, who dropped out too early in 2012 and missed out on a seesaw race where most everybody else got a turn at the top. And the last two winners of the Iowa caucus, Santorum and Huckabee, are perhaps clinging to hope that their old support their will re-emerge – Santorum, you’ll recall, was sixth in the polling just ten days before the last Iowa caucus, and wound up winning it and 10 other states.

(Via Nate Silver)

But odds of winning aren’t everything. There are four other questions a candidate has to ask at this point to decide whether it’s worth staying in the race:

One: What am I running to accomplish? [mc_name name=’Sen. Rand Paul (R-KY)’ chamber=’senate’ mcid=’P000603′ ], for example, is running in large part to act as the spokesman for a faction of the party that has no other logical spokesman in this field, and to prove himself at minimum a worthy successor to his father’s leadership of that faction. So, while Paul’s campaign has sputtered, he has a logical place in the field for some time. Younger candidates like Jindal, Cruz and Rubio can also take the long view of what they want this race to contribute to their careers (think of Al Gore’s campaign in 1988), and both Jindal and Fiorina may be angling for a VP slot or other job in the potential next Administration if they fall short of the big prize. But Graham, who has never been seen by anybody as a plausible nominee or a desirable VP, is running primarily to be a spokesman for his hawkish, internationalist, neoconservative foreign policy vision. The problem: there are already at least two other candidates on the big stage (Rubio and Chris Christie) and arguably one or two more (e.g, Jeb) who can articulate the same vision. Christie alone looks eager to walk across the stage and hit Rand Paul with a chair. This is why others like [mc_name name=’Rep. Peter King (R-NY)’ chamber=’house’ mcid=’K000210′ ] and John Bolton decided that running this time just to speak for that viewpoint would be superfluous (King was actually the first person to float a 2016 campaign and had made about a dozen visits to New Hampshire). And Graham’s not even on the first debate stage.

Two: Do I have the resources to keep going? That’s the big reason why Rick Perry, who in a just world would be one of the most serious contenders for this nomination, could end up dropping out before the voting starts – he’s playing to win, and he doesn’t seem to have the resources right now to keep going, having just lost his New Hampshire staff and his Iowa co-chairs. (One of my all-time favorite campaign moments was when Fritz Hollings was running in 1984 and had to hang up on a national TV telephone interview because he ran out of change for the pay phone). At the opposite end of the scale you have people like Jim Gilmore and George Pataki who have such threadbare campaigns that they aren’t really under any financial pressure to drop out despite the unserious pointlessness of their campaigns. This is the one area where Graham may not be feeling the heat, as he’s raised at least $3.5 million (two thirds of which was still cash on hand at the end of June) and has a few big SuperPAC donors. But to what end?

Three: Who is hurt by me staying in the race? This is one reason why I think Huckabee and particularly Santorum are wasting time in this race – there are other strong social conservatives with better odds at going deep into the race. In Graham’s case, he’s causing two problems besides what every candidate contributes to the overcrowdedness of the field. First, he draws such support as he has from the more hawkish, more mainstream and/or more moderate candidates – Rubio, Jeb, Christie, Kasich, Walker – which only weakens them vis a vis the populist immigration hawks, harder-core SoCons, and Paulists. And second, more specific to Graham, the one place he polls decently is his home state of South Carolina, one of the few key early states. If Graham gets out of the race, he could throw his endorsement behind one of the candidates who is closer to him ideologically, to some benefit. By staying in, he dilutes the value of South Carolina, the traditional GOP kingmaker state (before Newt Gingrich won it in 2012, South Carolina had voted for five straight candidates who won contested nominations, whereas Iowa has supported four losers since 1980, New Hampshire two).

Four: What else better do I have to do? This is the other key part of the equation for Graham. Of the other six candidates in the second-tier debate, five are out of office or retired from business now (Perry, Santorum, Fiorina, Pataki and Gilmore), and Jindal is term-limited and leaving office in January. The same is true of Huckabee, Jeb, and Carson. It’s easy to see why people like Gilmore, Pataki and Santorum have nothing better to do with themselves right now, and why Fiorina, Jindal and Perry see a continued campaign as possibly setting themselves up for something later, and how Cruz and Paul are building their mailing lists. But Graham is a sitting U.S. Senator, freshly re-elected and (despite conservatives’ fervent hopes of recruiting a serious primary challenger) quite possibly likely to be in the Senate for some time. His position as a leading foreign policy voice and his fits of bipartisan gang-joining make him, like it or not, a consequential Senator, and one whose influence is (not to put too fine a point on it) not dependent on grassroots national support. Spending the next five months on the road in Iowa and New Hampshire will only degrade his Beltway-based status, to no real purpose. (You could make some of the same arguments about Christie, but Christie at least is parlaying this run into a bigger national platform than he’d have from Trenton, and Christie will likely not win statewide office in New Jersey again, so it’s now or never).

Whether or not you like Lindsey Graham as a Senator, he matters in the Senate. He doesn’t matter in the presidential race, except to dilute the strength of like-minded candidates and the influence of his own home state. Go back to your day job, Senator Graham.