Nevertheless, Democratic presidential candidates are already running on agendas that implicitly demand the passage of progressive laws. Clinton's early calls for criminal justice reform, as widely noted, can make little progress without repealing many of the measures instituted in her husband's 1994 anti-crime bill. She has also endorsed a constitutional amendment establishing a right to same-sex marriage -- an even more ambitious ask from a right-wing Congress. Her only declared opponent, Bernie Sanders, is best known for proposals that somehow manage to be even less likely to reach his desk -- like a single-payer health care system, and expansions to Social Security.
This is madness on multiple levels. It dooms the Democratic agenda to four years of futile posturing and political theater, further undermining public confidence in the government. It severs any meaningful relationship between campaign platforms and policy outcomes, substituting a raft of dreams and quixotic aspirations for a plausible agenda. And most importantly, it abdicates the last and best tool the left has for overcoming the right's antidemocratic intransigence: executive action.
Liberals will flinch at the idea of candidates running on promises to make end-runs around the legislative branch -- but they shouldn't. The simplest reason is democratic accountability. As it stands, candidates simply aren't expected to articulate an executive agenda beyond indicating general dispositions on foreign policy. Pressuring them into doing so politicizes their plans, sets expectations, and creates the possibility of democratic feedback; it gives voters more control over their government.
The alternative defaults into the hands of the right: a presidency that is increasingly untethered from popular control, increasingly dictated by the powerful apparatchiks and lobbyists who will demand executive action. At best it ends in executive forbearance -- which in an era of legislative gridlock means governmental paralysis, again playing into the hands of the right.
That said, arguments that democracy is better facilitated by an archaic institution deliberately rigged to thwart it -- by overrepresenting landowners, by cynical gerrymandering, by supermajority requirements, and so on -- aren't particularly convincing. The presidency, too, is hobbled by the electoral college and the two-party system; nevertheless, it remains a far better instrument of popular control than the Congress. Moreover, those with a sentimental attachment to the Congress can console themselves with the reconfiguration of incentives an assertive presidency would impose on federal governance. It could force Congress to negotiate in exchange for continuing relevance, reversing the dynamic of polarization that has fomented much of the radicalism we see today.
It's easy enough to imagine all kinds of leftist policies and programs that could be implemented - or thwarted - by executive action. The limits of the president's authority, under the realpolitik norms governing our politics, are limited only by the democratic will and interpretive imagination.