Running mates? It's not even May, and already we're talking running mates? Then let me toss Elizabeth Warren's name into the mix.

I'm making several assumptions here -- in a year when assuming anything is dangerous. First, I believe Ted Cruz's desperate gamble of adding Carly Fiorina to his "ticket" will fail. He was right to throw some kind of Hail Mary, but I don't see how Fiorina attracts enough new support for Cruz to win the Indiana primary on Tuesday. And if he loses there, he's pretty much toast.

advertisement | advertise on newsday

Donald Trump's landslide wins this week in the Northeast gave him a bigger haul of convention delegates than even his most optimistic boosters had expected. If momentum still counts for anything in politics, Trump has it. And if he wins Indiana -- polls show him with about a six-point lead -- his path to the Republican nomination looks wide enough to taxi the rest of the way in his Boeing 757.

LettersYour election reflections2016 election2016 Voters Guide: What to know More coverageOpinion and analysis about the 2016 presidential campaign

I'm also assuming that Hillary Clinton will be the Democratic nominee. The delegate math is just brutal: There is simply no viable way now for Bernie Sanders to catch up. Sanders appeared to acknowledge reality this week when he announced that his campaign would lay off "hundreds" of paid staff members. He will use his clout at the convention, he said, to "put together the strongest progressive agenda that any political party has ever seen."
     Which is where Warren comes in.
     It is absurd to claim that Clinton does not merit the "progressive" label; she has the scars from decades of attacks by the "vast right-wing conspiracy" to prove her bona fides. But on most issues -- gun control being a glaring exception -- Sanders is well to her left. And, as his surprising campaign has shown, that's where the energy and excitement in the Democratic Party happen to be this year.
     If there is a specific issue on which Clinton is weak with the Democratic left, it is not the FBI investigation of her emails. It is her perceived coziness with Wall Street, highlighted by the six-figure speaking fees she was paid by investment bank Goldman Sachs.
     Sanders' central theme is that the rich and powerful have distorted our political and economic systems to favor their own selfish interests. He blasts Clinton not only for the Goldman speeches but also for mining Wall Street for campaign cash. My assumption is that Sanders, should he fall short of the nomination, will give Clinton his full-throated support. But will his most ardent supporters follow?
     As Clinton's running mate, Warren could erase this potential weakness with the Democratic base. She has spent her Senate career becoming known as the scourge of Wall Street. No political figure is more closely identified with efforts to curb the excesses of the financial system.
     Warren would also help address another potential vulnerability. If the general-election matchup is Trump vs. Clinton -- and that seems increasingly likely -- it is becoming clear that on the question of U.S. military involvement around the world, Trump will position himself to the left of Clinton.
     The foreign policy speech that Trump delivered Wednesday was, for the most part, vague and anodyne. His overarching theme is "America first," he said. To the extent the phrase means anything, it seems to promise that a President Trump would be extremely reluctant to deploy U.S. combat forces in any sort of "world's policeman" role. Trump has even questioned the viability of NATO in its present form.
     Clinton is a foreign policy traditionalist. As secretary of state, she was more hawkish than President Obama -- she pushed for more vigorous intervention in Syria, for example. She has long since apologized for her vote to authorize the Iraq War, but Sanders continues to attack her for it. Trump would surely do the same.
     Warren wasn't in Congress when the Iraq War began, and national security isn't the issue with which she is identified. But her views fit squarely with those of the party's progressive wing.
     Warren also has a compelling personal story of having risen from modest beginnings to become a Harvard professor and then a U.S. senator. The fact that she and Clinton would be the first all-female major party ticket should be irrelevant, but isn't. To many voters, it would be thrilling.
     I can think of several other potential running mates for Clinton. Funny, but I draw a blank when trying to come up with a suitable partner for Trump. Maybe he'll just go it alone.
    
     Eugene Robinson's email address is eugenerobinson@washpost.com.