Someday they will probably have to build a separate wing at the Clinton Library to house all the memos that are currently pouring into Hillary’s Brooklyn headquarters on how to run against Donald Trump . The bilious billionaire offers, as military strategists might put it, “a target-rich environment.”  

But for all the strategizing, Democrats still don’t know what version of Trump will be on display in the fall campaign.  

Will the short-tempered former reality-show host grudgingly make peace with Paul D. Ryan and other GOP leaders ? Will Trump modulate his tone and back off his extreme issue stances as he campaigns as a shape-shifting chameleon ? Or is the wall-building , Muslim-banning , insult-generating real-estate hustler too arrogant to change?  

At this point in the campaign, there are really only two near-certainties: Hillary Clinton will do nothing impulsively and the electoral map will be far more volatile than it was in 2008 and 2012. (Only two states — North Carolina and Indiana — changed sides in the two Barack Obama elections.)  

[Related: That Vast Chasm Between Clinton and Sanders] The biggest challenge that Clinton will face before the Democratic Convention is picking a vice president who will enhance her still-unfolding campaign strategy. As played out in the media, the VP game usually reflects a combination of self-serving leaks, out-of-nowhere speculation and idle entertainment.  

David Hawkings’ Whiteboard: Inside Clinton’s Voting Record 

But it doesn’t require much inside information to assume that the Clinton campaign has lumped its heartbeat-away possibilities into four rough categories:  

Bouquets for Bernie : While Hillary’s natural impulse would be to move to the center for the general election, the surprising and exasperating success of a Vermont socialist will pressure her in the other direction in the name of party unity.  

Sanders himself seems an unlikely choice because of mutual animosity and age, 75 on Inauguration Day. But Massachusetts Sen. Elizabeth Warren , whose relationship with Clinton is also frosty, would strongly appeal to the Bernie Brigade. As might two-term Ohio Sen. Sherrod Brown .  

The Constituency Calculus : Democrats tend to look at the electorate as a collection of interest groups. So even though Fla. Sen. Marco Rubio (the child of Cuban immigrants) and the Spanish-speaking Jeb Bush have fallen by the wayside, the Clinton campaign may still be tempted by a Latino running mate like HUD Secretary Julián Castro. In similar fashion, Hillary will probably mull picking a woman (maybe Warren or Minnesota Sen. Amy Klobuchar ) for the second-banana role. Her model would be Bill Clinton who doubled down in 1992 by tapping Al Gore , another young Southern moderate, as his VP.  

The Swing State Strategy: Ever since Lyndon Johnson helped deliver Texas for JFK in 1960, presidential nominees have been tempted by Electoral College arithmetic. This time around, such map-based strategies would point to both Virginia senators (Tim Kaine and Mark Warner ) as well as Ohio’s Brown.  

Trolling Trump: Another notion is finding a hatchet-wielding VP who will try to beat Trump at his own game. Elizabeth Warren (who does pop up on most of these lists) has been holding her own with Trump all week in the 140-character battlefield of Twitter. Even better with the shiv would be the other Minnesota senator, Al Franken , who might finally be persuaded to wield the comic talents that he honed on ‘Saturday Night Live ’ in the political arena.  

With Trump’s dismal approval ratings and recent polls that suggest that even Georgia could be in play in November, Clinton should be considered the favorite no matter whom she chooses as her running mate. But the problem is that none of these Democratic VP choices would help break the stalemate in Washington, which has been a major source of Trump’s anti-insider appeal.  

[Related: Republicans Couldn’t Muster the Honor to Fight Trump] This is an election that defies conventional thinking, which is why Clinton should be uncharacteristically bold in her vice presidential deliberations.  

Not since 1912 has a party split like the Republicans have in the wake of the Trump takeover. Even if Trump papers over his rift with Ryan, the Bush family and Mitt Romney (the GOP nominees in five of the last seven elections) have signed on as staunch supporters of #NeverTrump.  

There are obvious political reasons to exploit the GOP divisions, but the patriotic arguments are far more compelling. If ever there was a moment for a nominee to reach across party lines in the name of national unity, it is now with Trump the Vulgar Authoritarian attempting to storm the gates of the White House.  

Many Democrats will be quick to tick off the objections:  

[Related: Surrender, Bernie] Why should Clinton go out of her way to repudiate the liberal wing of the party that has flocked to Sanders? Why reward Republicans for eight years of nattering negativism in Washington? Why consider a VP nominee who doesn’t unequivocally support abortion rights, which has become the Democratic Party’s litmus test issue?  

The answer to all these complaints boils down to two words: President Trump. American democracy is in peril, which, alas, is not partisan hyperbole.  

This is an election when Democrats, as well as Republicans, need to put country ahead of party.  

It is tempting to play the name game, as a few prominent Republicans who support abortion rights come to mind like former New Jersey Gov. Christie Todd Whitman and Nevada Gov. Brian Sandoval .  

But an even bolder choice would be a retired public official who shares Clinton’s long history with health care reform. This prominent Republican has pledged to do almost anything to stop Trump from an Electoral College victory. And he rivals Hillary both in intellect and seriousness of purpose.  

It won’t happen, of course. But I love imagining a Hillary Clinton-Mitt Romney ticket carrying all 50 states against Trump in November.  

Roll Call columnist Walter Shapiro is a veteran of Politics Daily, USA Today, Time, Newsweek and the Washington Post. He is a lecturer in political science at Yale. Follow him on Twitter @MrWalterShapiro. Get breaking news alerts and more from Roll Call on your iPhone or your Android.