Michael Bloomberg is a Democratic candidate for president. The views expressed in this commentary are his own. View more opinion on CNN.

(CNN) The foundation of our democracy, the right to vote, is under attack across America by Republican leaders who are trying to make it harder to register and cast a ballot.

Last week I was in Georgia with Stacey Abrams, who narrowly lost her Georgia gubernatorial campaign after her opponent, then the state's secretary of state, engaged in voter suppression tactics including purging voters from the rolls. I've been glad to support the nonprofit group she started, Fair Fight, to ensure that everyone with the right to vote can easily vote.

But as we Democrats work to protect democracy from Republicans who seek to exclude voters, we must also look inward, because our own party's system of nominating a presidential candidate is both undemocratic and harms our ability to prepare for -- and win -- the general election.

It's true the party has come a long way from the days of candidates being selected in smoke-filled back rooms by party bosses. But our current system—in which two early states dominate the candidates' time and resources—is in urgent need of reform.

The Democratic Party reflects America's incredible diversity. But the first two voting states, Iowa and New Hampshire, are among the most homogenous in the nation. While it's great that candidates reach out to voters in these states at every pancake breakfast and town hall around, what about African-American, Latino, Asian American, Pacific Islanders, and other voters in places like Detroit, Montgomery, Phoenix, and Houston? I've visited them all recently, and almost to a person, voters tell me the other campaigns have almost no presence in their cities.

The problem is compounded by the fact that the two early voting states are unlikely to be consequential in the general election. So as a party, we are spending all of our time and resources outside of the battleground states we need to win.

Meanwhile, President Trump is spending his time in Michigan, Wisconsin, Ohio, Pennsylvania, Florida, and North Carolina -- all states we lost in 2016 by razor-thin margins. In 2020, we need to reverse at least some of those results -- and we also have the chance to flip other states that voted for Trump, including Arizona and even Texas.

But right now, we are in danger of repeating 2016 in large part because, as Democrats focus on Iowa and New Hampshire, Trump is operating at full-speed in the battleground states, with field staff and targeted television and digital advertisements. Tuesday, while Democrats are on stage in Des Moines, he'll be speaking to thousands of supporters in Wisconsin — a state Democrats need to rebuild the Blue Wall.

About two months ago, when I looked at the uphill battle Democrats face against President Trump, I decided I had no choice but to run. I'm sometimes asked if I'm trying to buy the election. My answer is simple: Know a better use for my money than defeating Donald Trump?

In swing states across the country, our campaign is registering voters, funding anti-Trump digital ads, and building field operations. And we'll be keeping field offices in these states open through the general election, no matter who our party nominates.

Our campaign has made steady progress in the polls very quickly, but people often ask me: Why aren't you in the debates?

It's simple: The party requires candidates to have a certain number of donations, but I've never accepted a nickel from anyone. Unlike President Trump, I've always been independent of the special interests.

I hope the DNC changes its rules -- I'd gladly participate -- but I'm not going to change my principles. So I'm traveling the country taking my message directly to voters -- and as a result, President Trump is now finally facing opposition from a candidate in the battleground states. No wonder his last five rallies have been held in swing states where I'm campaigning aggressively. But I shouldn't be the only candidate who is regularly campaigning outside of a small handful of states.

The traditional justification for giving two small states so much influence is that larger states require more money. But with social media platforms and cable news, there are few barriers to getting a message out -- that's why more than two dozen Democrats entered the race.

As president, I will ensure the DNC works with state party leaders at every level to re-order the primary calendar in ways that better reflect our diverse electorate and channel more resources into the states we actually need to win in November. This will build on the good work done by the party's National Unity Commission to broaden the party's base, empower Democrats at the grassroots level, and make our party competitive in every region of the country.

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Julián Castro deserves credit for being a leading voice on these issues during his presidential run. But since the changes are unpopular with voters in Iowa and New Hampshire, the other candidates have mostly stayed mum. I'm speaking up because it's the right thing to do for our party and country, and I hope more Democratic leaders around the country will join me.

Don't get me wrong: I have enormous respect for the voters of Iowa and New Hampshire. Both states are full of devoted citizens. But so are the other 48. And we need a system that both better reflects our country and puts us in a better position to defeat a candidate like Donald Trump.