Washington (CNN) Democratic presidential candidate Michael Bloomberg used a CNN op-ed Monday to blast his party's outsized emphasis on Iowa and New Hampshire, saying such a focus risks ignoring battleground contests.

The former New York mayor's op-ed, which said the early-voting states lack diversity, was published hours before Cory Booker, one of the most prominent black candidates running for president, suspended his campaign , again drawing attention to a lack of racial diversity atop the Democratic field. Booker's exit leaves just three candidates of color in a race that at one point was largely defined by its exceptional amount of diversity

"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," Bloomberg wrote in the op-ed. "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?"

Bloomberg, a late entrant into the presidential field , has chosen to ignore the early-voting contests , opting instead to focus his time and money on other states across the country, including those that Democrats are looking to win back from President Donald Trump in November. His op-ed, published on Monday, comes three weeks before the Iowa caucuses, the first contest of the nominating process, and nearly a month before the New Hampshire primary.

The op-ed represents a shift in Bloomberg's position from as recently as last week, when he told reporters in Ohio that "the system has gotten used to" the current slate of early-voting states leading the process, "and I guess the Democratic Party probably shouldn't take it away."

Read More