Republican opposition to the so-called Buffett rule successfully blocked the proposal from advancing in the Senate on Monday. It would have created a new tax for earners who bring in more than $1 million in annual income. 

President Barack Obama has been vocal about the need for such a rule since his State of the Union address earlier this year. The Senate voted 51-45 to block the measure, mostly along party lines, with Sen. Susan Collins of Maine casting the lone Republican vote with Democrats. 

Collins’ willingness to vote against her party is noteworthy in Hawaii because former Gov. Linda Lingle recently said that if she’s elected to the U.S. Senate next year, she’ll look to fellow Republican Collins as a role model. Rep. Mazie Hirono, a Democrat who’s vying for the same Senate seat, said she was disappointed by how things went in the Senate.

“Many of the most fortunate individuals, such as billionaire Warren Buffett, think it’s unfair that they pay lower tax rates than their middle class employees,” Hirono said in a statement. “I agree. We all recognize that what we really need is comprehensive tax reform that is fair and progressive and promotes investment, savings, and entrepreneurship.”

President Obama also released a statement Monday night. Here’s part of what he had to say:

“We simply cannot afford to keep spending money on tax cuts that the wealthiest Americans don’t need and didn’t ask for. But it’s also about basic fairness — it’s just plain wrong that millions of middle-class Americans pay a higher share of their income in taxes than some millionaires and billionaires.”