At first glance, it may seem remarkable that 15 Senate Democrats -- including three considered most vulnerable to losing their re-election campaigns in November -- signed a letter last week encouraging the Environmental Protection Agency to delay its planned issuance of a controversial new regulation. That regulation would limit carbon emissions by power plants that burn coal, which generate almost half of America's electricity.

The 15 Democrats were joined by 30 Republican senators in asking EPA Administrator Gina McCarthy to double the usual public comment period from 60 days to 120 days. With the EPA set to unveil the rule on June 2, the normal comment period would put issuance of the final version of the new regulation right at the outset of the most crucial phase of the 2014 election campaign. With the 120-day comment period, that won't happen until after the election. (Curious, isn't it, that 30 GOP senators support something that would aid vulnerable Democrats in November?)

The three most vulnerable Democrats are Sen. Mary Landrieu of Louisiana, Mark Pryor of Arkansas and Mark Begich of Alaska. Landrieu and Begich represent states with rich oil and natural gas resources, while Pryor confronts an electorate that has voted red in national elections. The letter this vulnerable trio signed argues that “affordable, reliable, and redundant sources of electricity are essential to the economic well-being of our states and the quality of life of our constituents. While we all agree that clean air is vitally important, EPA has an obligation to understand the impacts that regulations have on all segments of society.”

These three Senate worthies are likely most concerned about themselves: They know the new EPA rule will mean a huge boost in electricity prices across the country. The rule is a key part of the program President Obama had in mind when he conceded in 2007 that “electricity prices would necessarily skyrocket” under his administration. The carbon emissions ceiling under the proposed EPA rule would be impossible for most, if not all, of the country's 1,308 coal-fired electricity generating power plants to meet.

The new rule comes on top of another key component of the Obama program, the EPA's Mercury and Air Toxic Standards that take effect in 2015. The MATS compliance period may be extended a year by state environmental authorities, but that will only delay the consequences until 2016. Arkansas is among the most coal-dependent states in the country, according to the Union of Concerned Scientists. No wonder Pryor wants to delay the EPA rule until after Arkansas voters choose between keeping him in the Senate or electing his Republican challenger, Rep. Tom Cotton.

The letter encourages McCarthy to remember that "the upcoming proposal will be far more complex and critical for the industry to deal with than the proposal for new plants, and stakeholders will need time to analyze the rule and determine its impact on individual power plants, reliability and consumer cost, and on the electric system as a whole." Voters may ask why these senators are just now realizing that fact.