As Colorado’s Republican and Democratic primaries for governor hit the final stretch, campaign finance reports filed Monday detail a big-ticket race that continues to set records, with two self-funding candidates accounting for roughly $9 million of the nearly $15 million spent so far.

The latest totals confirm predictions that the race to succeed term-limited Democrat John Hickenlooper will be the most expensive gubernatorial contest in state history.

With six months to go until the November election, the $15 million in candidate spending has already surpassed the roughly $10 million total spent each of the last three times Colorado has elected a governor, and there’s no sign it’s slowing down.

Four Democrats and four Republicans are vying for their parties’ nominations in the June 26 primary. By nearly every measure, Democrats outpaced Republicans for the reporting period, which covered money raised and spent from Jan. 1 to May 2.

After adding $5 million to his own campaign coffers since the first of the year – bringing his total self-funding to around $6.3 million – U.S. Rep. Jared Polis, one of the wealthiest members of Congress, spent just over $6 million for the period. The Boulder Democrat finished the quarter with about $500,000 in the bank.

Cary Kennedy, a former state treasurer, raised about $800,000 in contributions during the period, more than any other candidate in a single fundraising period this cycle. After spending $1.2 million, the Democrat  had $435,000 on hand.

Mike Johnston, another Democrat and a former state senator, raised $600,000, bringing his total to $2.1 million since he launched his run – more money than any candidate for governor from either party has raised in a contested primary. After spending about $1.2 million, he has $838,000 on hand, the most of any candidate this period.

And Democratic Lt. Gov. Donna Lynne raised $337,000, including a $100,000 contribution to her own campaign, bringing her total fundraising to just above $1 million. After spending around $700,000, she had about $300,000 in the bank.

In the Republican primary, state Treasurer Walker Stapleton brought in the most money, while businessman and former state lawmaker Victor Mitchell, who loaned his campaign $3 million when he launched it a year ago, turned on the spending.

Stapleton collected just shy of $400,000 for the period, spent $584,000 and had $831,000 in the bank. He’s pumped $285,000 into his campaign.

Mitchell, meanwhile, spent $2.8 million – largely on heavy TV advertising, which his campaign says he plans to continue through the primary – and was left with about $260,000 in the bank.

Doug Robinson, a Republican, retired investment banker and Mitt Romney’s nephew, raised $90,000 and spent $650,000, leaving him with just under $100,000 on hand. He’s loaned himself $300,000 over the course of his campaign.

The fourth GOP candidate, former Parker Mayor Greg Lopez, has been running a lean campaign in comparison to the others. He raised just under $7,000 for the period, spent $33,000 and had about $7,000 in the bank. That figure includes $24,000 he’s loaned himself.

Campaign finance reports will be due every two weeks until the primary.