David Frum gives some bad advice:

Warren plainly does want to do things—and is denying herself her best chance to get them done [bold mine-DL].

If Elizabeth Warren did seek the Democratic presidential nomination, she’d seize the party and the national agenda. Rank-and-file Democrats seethe with concern about stagnant wages, income inequality, and the malefactions of great wealth.

Left to her own devices, Hillary Clinton will talk about none of that.

This is a trap for Warren. If she does want to get anything done on the issues that she’s interested in, she won’t waste a large part of the next year running a quixotic protest campaign. She might not be able to do anything while Democrats are in the minority, but it is possible that they won’t be in the minority in the Senate for all that long. Depending on how a few 2016 Senate races turn out, Democrats could control the chamber again by 2017. If the goal of a protest run is to define the party’s agenda, Warren is already doing that more effectively where she is than any of the would-be challengers to Clinton so far. A presidential campaign at this point would be an unnecessary distraction.

Frum also imagines that Warren could not only force Clinton to talk more about her main issues by running, but could even win the nomination:

Could Warren do it? Of course she could. More than almost anybody running in 2016—more even than Republican insurgents like Ted Cruz and Rand Paul—Warren has both her message and her constituency ready to hand.

I would like to believe it would be possible for a challenger to defeat Clinton again, but it isn’t. For one thing, Democrats went with the insurgent challenger the last time there was an open contest for the nomination, and the Obama presidency that came from that has left many progressives disillusioned on a range of issues. I assume Democratic voters aren’t going to want to take a chance on another insurgent. I don’t doubt that Warren could generate considerable enthusiasm on the left, but why should disillusioned Obama supporters believe that she could deliver better results?

As Robert Golan-Vilella noted on Twitter, Frum overlooks the obvious gap in Warren’s record:

…how do you seriously run for president without any background, interest in, or really message at all on foreign policy? (2/2)

— Rob Golan-Vilella (@RGolanVilella) January 14, 2015

I’ve said before that Warren doesn’t need to spend much time focusing on foreign policy issues when her main interests are in domestic policy, but that takes for granted that she won’t run for president. In order to run a semi-credible protest campaign, Warren would have to be able to speak competently on those issues, and to date there’s not much evidence that she is prepared to do that. Warren should focus on doing her job, since that is where she is most likely to have some chance of advancing her agenda.