How the Oregon primary works
PORTLAND — Voter turnout is usually tepid during primary season compared to the November general election. But this year's wild presidential election has generated a surge of interest in the primaries, largely because of the unexpected popularity of Republican Donald Trump and Democrat Bernie Sanders.
In Oregon, roughly 160,000 voters proactively took steps this year to make themselves eligible to cast a presidential ballot during its closed primary on Tuesday.
But the heightened interest has also stirred some frustration over the primary system. The criticism varies but generally targets states such as Oregon where large groups of nonpartisan voters are excluded from the primary, and superdelegates who sometimes don't have views aligned with their electorate.
About 30 percent of Oregon's 2.3 million registered voters aren't allowed to cast a presidential ballot, nor for other partisan races such as governor and secretary of state, during the primary.
Here's an explanation of how Oregon's primary works.
Who can vote on Tuesday and why?
Unlike the November general election that includes all voters, Oregon's May 17 presidential primary is "closed." Only voters who are registered as Democrats or Republicans can pick a presidential nominee on their ballot, as well as governor and other partisan races.
Tuesday's contest also marks the first state-run primary for the Independent Party of Oregon, which became the state's third official major party last year. That election is open to registered Independents and also nonaffiliated voters, the state's third biggest group of voters behind Republicans. The latter group had to notify their county elections officials to request an Independent ballot, so it's unclear what their turnout will be on Tuesday.
Because the Independent Party doesn't have a presidential candidate, voters must write-in their pick for the nominee. But any Independent votes for the Democratic or Republican candidates won't be accounted for in those parties' results on Tuesday because of their closed primary structure.
Who decides the primary structure?
The parties, not the state, decide whether their primaries are closed, mixed or open to all voters. That's why Democrats' and Republicans' contests are closed, and Independents opted to include nonaffiliated voters. They also decide other rules around delegates and superdelegates, for example. The parties do, however, have to operate within certain guidelines set by state law.
Such limitations on the electorate have been a source of contentious discussion this year. Some prefer an open primary system such as Vermont, where no party affiliation is required to cast a ballot, while others defend the current structure as a way to protect a party's values and political platforms ahead of the November general election when all voters, like-minded or not, get involved.
What are delegates and superdelegates, and how many does Oregon have?
Oregon has 102 total delegates — 74 for Democrats and 28 for Republicans. That's a relatively small tally determined by Oregon's population relative to other states.
Delegates and superdelegates represent their states at the national Democratic and Republican conventions. That's when, say, Donald Trump would transition from presumptive GOP nominee to official nominee on the November ballot. There's also the potential of the unusual scenario, as Sanders is hoping, of determining the winner of a contested race.
Delegate rules vary widely, but they're generally required to vote for their home states' preferred candidate at the convention, at least during the first round of voting.
Included in Oregon's delegate count are 13 Democratic superdelegates, who include Gov. Kate Brown and U.S. Sens. Ron Wyden and Jeff Merkley, for instance.
Superdelegates are usually high-ranking political figures with the freedom to vote for whomever they want at the conventions — another point of contention this year as their votes are sometimes at odds with their electorate and they carry enormous weight at the national conventions.
That scenario has already been playing out in Oregon, where voters lean with Sanders while Brown, Wyden and a few other superdelegates endorsed front-runner Hillary Clinton.
Oregon's GOP used to have three superdelegates, but amid all the scrutiny, eliminated them last month.
How are delegates decided?
Some states have a winner-take-all (or most) approach, meaning the candidate with the most votes takes all the delegates.
Oregon, and other states, dole out delegates proportionally to how the electorate votes in the primary. So while the results from Tuesday are moot for the GOP, where Trump no longer has opponents, they're more important on the Democratic side, where Sanders needs a strong turnout to help him close in on Clinton's massive delegate lead.