Ever since Democrats began linking GOP Senate candidates to the billionaire Koch brothers, Republicans — and plenty of neutral commentators — have sneered dismissively about the strategy. It could only be about pumping up Dem fundraising; or it was a desperate ploy to distract from Obamacare; or it was merely about driving up Republican candidates’ negatives.

The counter-argument is that this strategy is also about contrasting the two parties’ policy priorities. It’s about making the case that there really is substantial overlap between the GOP agenda and the Koch brothers’ push for an anti-tax, anti-regulatory, anti-government-interventionist agenda that, as the New York Times has detailed, benefits their bottom line. The Dem argument is that voters deserve to know why the Kochs are investing so much in a GOP Senate — which of course benefits Republican Senate candidates.

Today Sam Stein scoops that several GOP Senate candidates, in a private gathering, confirmed their reliance on the Koch brothers and the depth of their influence:

Three top Republican Senate candidates heaped praise on the political network built by the conservative billionaires Charles and David Koch during a secretive conference held by the brothers this past summer, according to audio of the event.

Iowa state Sen. Joni Ernst and Arkansas Rep. Tom Cotton directly credited donors present at the June 16 retreat in Dana Point, California, for propelling them forward. Colorado Rep. Cory Gardner told attendees that his race would likely be decided by the presence of “third party” money — an obvious pitch for generosity from the well-heeled crowd.

Ernst credited the Koch network with having “really started my trajectory.” Cotton heaped praise on the Koch-founded Americans for Prosperity for transforming Arkansas politically in ways that help Republicans. Gardner said the cash from the Koch network could prove decisive.

There is nothing necessarily wrong with any of this. But it undercuts GOP complaints about the Dem strategy of targeting the Koch brothers and linking GOP candidates to them. Republicans have fretted that this is all about a concerted strategy to “demonize” big GOP donors. But there is no reason why the actual agenda and motives of individuals who are wielding so much influence over who will control the Senate should be off limits, just as there is no reason why billionaire environmentalist and major Dem donor Tom Steyer’s agenda and motives should be off limits.

In that context, it’s highly significant that the GOP Senate candidates themselves have confirmed the true dimensions of that influence.

* OBAMA PUSHING FOR GLOBAL CLIMATE DEAL: The administration is trying for a 2015 global deal to get major countries to limit carbon emissions. But Republicans won’t help supply the Senate votes to ratify any legally binding treaty, so here’s what the administration may do to get around this:

President Obama’s climate negotiators are devising what they call a “politically binding” deal that would “name and shame” countries into cutting their emissions. The deal is likely to face strong objections from Republicans on Capitol Hill and from poor countries around the world, but negotiators say it may be the only realistic path.

Worth noting: Republican opposition to a global climate deal will flare up right in the middle of the 2016 GOP presidential primary, making ratification even harder.

* A GOVERNMENT SHUTDOWN OVER DEPORTATIONS? HuffPo’s Igor Bopic reports that Marco Rubio is now hinting that Republicans could use the budget process this fall to try to block any Obama executive action on deportations. Rubio:

“There will have to be some sort of a budget vote or a continuing resolution vote, so I assume there will be some sort of a vote on this. I’m interested to see what kinds of ideas my colleagues have about using funding mechanisms to address this issue.”

Imagine Ted Cruz and other conservatives trying to force House GOP leaders to use the government funding showdown against deportations just as they did against Obamacare last year. A shutdown push to block deportation relief! Great optics!

* FOR GOP, BATTLE OVER DEPORTATIONS ISN’T GOING AWAY: Meanwhile, check out what Rubio has to say about Obama’s coming action on deportations, whatever it is:

If the GOP does win Senate control, and Obama takes unilateral action — a move Rubio believes would far exceed the president’s constitutional authority — Rubio foresees Republican lawmakers voting to overturn the executive order. “That’s something we would have to consider,” Rubio said. “In fact, I think that’s something I would advocate that we do in conjunction with putting in place meaningful reforms about how to enforce our immigration laws.”

Yep! As I’ve been saying, Republicans will face pressure to roll back Obama’s actions, which means the numbers of those who will lose protection against deportation if Republicans get their way will only climb higher.

* GOP CANDIDATES MUM ON BIRTH CONTROL MANDATE: A nice catch by Elise Viebeck: Republican Senate candidates have stayed silent on Obama’s newly-announced changes to the birth control coverage mandate, even though they are being criticized by the religious right:

Republican consultants said candidates would be foolish to risk comments that could alienate female voters at this stage of the campaign with Democrats so ready to pounce on the “war on women” message”

Wait — haven’t GOP strategists assured us that the Dem emphasis on women’s issues is a failed effort to distract from the issues that voters really care about, i.e., Obummercare?

* NEW ADS IN SENATE RACES: The DSCC is up with a new spot in Michigan hitting Terri Lynn Land over her opposition to abortion and equal pay legislation. Meanwhile, Dem Senator Jeanne Shaheen is up with an ad in New Hampshire tying Scott Brown to Big Oil.

Guess what: Individual races may well get decided around different issues, and Obamacare may not be the only issue that matters!

* AND SENATE DEMS UPSET ABOUT PUSH FOR WAR VOTE: An interesting report from the Hill: Senate Democratic aides are angry at Senator Tim Kaine for pushing for a vote to authorize the bombing campaign against ISIS. Note these:

“Asking anybody to take that vote within two months of an election is just stupid. Why would you put people in that position?” said a Senate Democratic aide. “I think it’s dumb,” said the second Democratic aide. “The less the president is in the news with anything right now, the better.”

Yes, some folks want lawmakers to vote on hugely consequential matters such as whether to go to war! It isn’t easy being a Senator, is it?

Greg Sargent writes The Plum Line blog, a reported opinion blog with a liberal slant -- what you might call “opinionated reporting” from the left.