Jack Graham, left, and Robert Blaha.Denver Post file WASHINGTON — Drawing upon their personal wealth, two candidates in Colorado’s race for U.S. Senate have dominated the spending in the five-way fight for the Republican nomination, more than doubling the combined amount paid by their three opponents for television ads, yard signs and other campaign expenses. Together, businessmen Robert Blaha and Jack Graham have spent more than $1.9 million through June 8, about twice the roughly $882,000 paid by rivals Ryan Frazier, Darryl Glenn and Jon Keyser, according to federal fundraising records.