(CNN) Hillary Clinton has won the Democratic Party nomination. Now, two things are important. The first is that Clinton defeats Donald Trump in November. The second is that Clinton should aim to build a true coalition of centrist and progressive politics, uniting the two wings of the Democratic Party.
If she sticks with the Clinton tradition of "triangulating" with Republicans, she risks not governing at all; a Trump victory would be a real possibility.
 
If the United States were a parliamentary system, Clinton and Bernie Sanders would not even be in the same party. Clinton would be a center or even center-right party in the European scene, perhaps an Angela Merkel leading the Christian Democrats. There is little that is truly progressive about her politics. Sanders would be leading the Social Democrats, representing the party of trade unions, progressive taxation and regulation of Wall Street.
 
It is not unusual for centrists and social democrats to govern together, especially when a major goal is to keep out right-wing and anti-immigrant populist parties. But let's have no doubt: This would be a coalition, not a unity of forces. The happy talk of "unifying" a single Democratic Party is an Americanism that I believe is reaching the end of its usefulness. By 2020, it is quite possible that we will actually have four major political parties: a social democratic left, a centrist party, a right-wing conservative party and a populist anti-immigrant party (represented by Trump followers).
 
What would a coalition mean? It would mean not just a party platform with some happy talk of progressivism. Party platforms are what economists call "cheap talk." They mean almost nothing. They have almost no effect on actual governing since America does not have party-led governance. It has an executive branch led by a president, and shifting coalitions in Congress that do not heed any party's platform.
 
A coalition would mean a sharing of Cabinet positions. This too is fraught with ambiguity. I don't mean that a President Clinton would designate a set of candidates that would check the boxes with various ethnic, social and political constituencies. I mean that certain key Cabinet positions would be allocated to Bernie Sanders and his faction (and perhaps a separate party four years from now).
 
From the perspectives of the social democratic wing, Clinton comes with heavy baggage, of which three are most important. The first is her long-standing romance with Wall Street. It was Bill Clinton's political maneuver in 1992 to form an alliance of the Democrats and Goldman Sachs (Bob Rubin) that has defined the modern Democratic Party. It is at the root of the financial excesses of the past 20 years. We know that Wall Street remains a major Clinton funder and a serial breaker of the laws.
 
The second is her long-standing romance with the military-industrial complex. This too goes back to the Clinton presidency, with the Iraq Liberation Act in 1998 and the bombing of Belgrade, Serbia, in 1999. Since then, Hillary Clinton has been a strong supporter of the U.S. war in Iraq (2003), the U.S. military efforts in Libya (2011) and covert operations in Syria (from 2011 Clinton also has close links with Saudi Arabia, which has been a funder of the Clinton Foundation, and is the CIA's partner in the war in Syria. The progressive wing of the Democratic Party is distraught with Clinton's hard-line approach, which is even more militaristic (though less bigoted) than Trump's, as well as with her close ties with the Saudi regime.
 
The third is the twisted conflicts of interests that connect the Clinton Foundation and the U.S. government. Those of us who work in international economics have watched for years as elementary ethical boundaries are blurred or ignored. The email scandal is not a one-off proposition. It is a reflection of the Clintons' arrogance to think they can get away with chronic ethical lapses. So far they have. To end this conflict of interest, I would strongly urge the suspension of the Clinton Foundation during any Clinton presidency. The foundation's functions could easily be taken up by CARE, Save the Children and other nongovernmental organizations.
 
What then would be a coalition that could bridge the centrist and progressive factions? Sanders and his team should have their say over the Treasury secretary and at least one of the four key foreign policy positions: national security adviser, secretary of state, secretary of defense and head of national intelligence. To leave all four of the hard-power positions to Clinton would be to invite catastrophe, an expansion of war in the Middle East, a new Cold War (or God forbid a hot one) with Russia over NATO expansion, and nearly unchecked covert operations by the CIA.
 
It is true that such formal coalition politics are not normal for the United States. On paper we are a presidential system in the executive, and a geographically based, not party-based system in Congress. There is no overarching government as in parliamentary rule.
 
Still, we are not in normal times. Both parties' nominees have record-high disapproval ratings in part because the candidates represent only one ideological faction of their respective parties: Clinton, the centrists, and Trump, the anti-immigrant populists. They are deeply distrusted, even loathed by some, in the other part of their parties, such as Ryan Republicans and Sanders Democrats.
 
As Sanders has rightly declared, defeating Trump is a national priority. I will certainly vote for Hillary Clinton. I would like to campaign for her as well but that would depend on the confidence that her administration would end its disastrous romance with Wall Street, end its relentless militarism and end the Clintons' chronic shirking of ethical standards and clarity. In the meantime, it's also not too soon to start building a true social democratic party for the future.

http://www.cnn.com/2016/06/09/opinions/clinton-sanders-coalition-opinion-sachs/index.html