If you look at the Democratic nominees for president since 1932, those that have won have done so by stressing economic liberalism. "Economic liberalism" uses the power of the government to expand economic opportunities for all Americans, but especially for working class Americans, or by increasing the social safety net.
Examples are Social Security, Medicare, minimum wage laws, allowing unions to organize, work place safety laws, regulations regarding corporate activities, and laws regulating damage to the environment. When political campaigns are fought over these kind of issues, it is much easier for Democrats to win.
When, however, they are fought over issues of social liberalism, however, it is much more difficult for Democrats to win. "Social liberalism" uses the power of the government to change the way people in our society interact with each other. Examples of such laws are laws that change gender rules, change racial rules, and change sexual rules.
Another example of "social liberalism" would be using the power of the government to change personal behavior. An example of such use would be outlawing the ownership of certain firearms, or regulating their use and possession.
"Economic liberalism" pits the interests of the overwhelming majority of Americans against the interest of economic elites. "Social liberalism" often pits the interests of one group of Americans against another group of Americans. When that happens it is much easier for Republicans to win.
This is because each party's strength is also its weakness. The strength of the Republican party is that it is relatively homogeneous. It is mostly white, mostly middle class to upper class, mostly religiously conservative, and mostly run by males. Because they are more alike, it is easier for Republicans to get along and more difficult for Democrats to peel votes away from Republicans.
The Democratic Party is a coalition party. The strength of the Democratic Party is that it is easier to attract new voters to a coalition party. If you look at the voting history of immigrants to America, they often start out voting Democratic. That was true of the Irish and Italians and it is true of Hispanics today.
The weakness of such a party, though, is that it is easier to peel votes away from the coalition by arguing that one part of the coalition is inherently opposed to another part of the coalition. An example of such tactics is the so-called "Southern Strategy" used by Nixon, and Republicans since Nixon, to carry the South. The genesis of this strategy was southern white resentment over the passage of Civil Rights laws under the Johnson administration.
What Democrats need to do, then, is to stress economic liberalism over social liberalism. This doesn't mean giving up on issues like civil rights for minorities, or fighting for equal employment laws for women. What it does mean, though, is stressing policies that help middle class and working class Americans. In political campaigns, it isn't just the policies that are important, it is the tone in which the campaign is run.
Another example of