MIAMI – Florida is a state where elections are often decided by the slimmest of margins and the old adage "every vote counts" is especially true.

But according to WPLG-TV in Miami, about a third of all registered voters in Florida are blocked from participating in voting in primaries to choose the candidates that go on the November ballot. That's because Florida is a closed primary state, so only registered party members may vote for their parties' candidates.

In Florida, a closed primary is especially significant because almost a third of all registered voters -- 3.5 million people -- choose to remain "NPA," meaning no party affiliation, or are registered with a minor party other than Democratic or Republican. And the trend to remain party-free is increasing yearly.

For congressional and state races, Florida is one of 10 states where primaries remain completely closed. The others are Oregon, Nevada, New Mexico, Kentucky, Pennsylvania, New York, Maryland, Delaware and Connecticut.

Nineteen states have open primaries and 18 states have rules that vary by party. In Washington and California, primary ballots for congressional and state races are nonpartisan, listing all candidates from all parties, with voters asked to select their top choice. The first- and second-place candidates go on to the next round.

While a closed primary forces many registered voters to sit on the sidelines, disenfranchised from the first round of choosing candidates, advocates argue that only people who belong to a party should choose their leaders.

There is also concern that allowing unaffiliated or opposing party voters to cast ballots opens a primary election to potential manipulation or sabotage.

A grassroots groundswell of support for open primaries has taken root in recent years, arguing that since all taxpayers pay for primary elections, all taxpayers therefore should be able to participate.

The 2018 Florida Constitutional Revision Commission rejected a proposal to put the question of open primaries on Florida's November 2018 ballot as a potential amendment to the state Constitution.

Currently, supporters of the nonpartisan, top-two open primary process are collecting signatures for a petition to get the question to voters on the 2020 Florida ballot.