Majority Leader Harry Reid (D-Nev.) canceled a weekend Senate session Friday while issuing a serious warning to President Barack Obama and Speaker John Boehner (R-Ohio), who are now negotiating a debt deal without him: Don’t neglect the interests of Congressional Democrats.

Earlier this week, Reid had planned to keep Senators in town so he could start the procedural process on a bill of last resort that he crafted with Minority Leader Mitch McConnell (R-Ky.) to raise the nation’s debt limit before the Treasury’s Aug. 2 default deadline. Thursday morning, Reid even took to the floor with Democratic Conference Vice Chairman Charles Schumer (N.Y.) to say the House was putting the country at risk of default by recessing for the weekend.

But by Thursday evening, it had become clear to Reid that momentum had shifted from his Senate-first pathway to a House-first framework based on the renewed talks between Obama and Boehner — and that his services, and those of his chamber, were unnecessary.

Following a contentious Conference meeting Thursday afternoon and a White House meeting with House and Senate Democrats that few will discuss, Reid sent his Members home and tersely wished Obama and Boehner “well.” But the Nevada Democrat did not seem happy in doing so.

“I say to both the president and to the Speaker here on the Senate floor, representing my Democrats and, I’m confident, many Republicans: Be very careful,” Reid said. “Show a lot of caution as this negotiation goes forward because any arrangement must be fair to all America, not just the wealthy.

“We await their efforts,” Reid said of the ongoing Obama-Boehner talks, which are looking at $3 trillion in savings and a potential future “promise” for tax code reform. “I’m told there will be revenue measures in that. If that’s the case, we know constitutionally this matter must start in the House of Representatives.”

As of Friday, however, it was unclear that revenues are part of the package, or at least in a way that will satisfy Democrats in the House and Senate, both of whom will be needed to clear any agreement.

Senate Democrats, typically more willing to stand in line with the president, began to speak out Friday after voting to table the House-passed Cut, Cap and Balance plan. They were particularly incensed about being kept out of the loop on the ongoing talks and accused Office of Management and Budget Director Jacob Lew of being less than forthcoming in their Thursday meeting.

Democratic Senators were huddled for their weekly luncheon Thursday, listening to Lew address the Conference, when their BlackBerrys began to buzz with news of the Obama-Boehner dealings. That’s when Members started getting vocal and frustrated that their concerns weren’t being addressed.

“I don’t lose my cool, and I lost it yesterday,” Sen. Dianne Feinstein (D-Calif.) said Friday. “I’ve never seen frustration higher.”

“My understanding is that we’re not included” in the talks, Feinstein continued, “and he had no idea discussions were even going on. … I like to know what I’m doing and I can’t get any information, and it’s very frustrating. It’s very hard. It’s easy to pass something and say one year or so later, ‘Oh my god, I didn’t realize I did that.’”

Feinstein then echoed what many of her colleagues, including Sen. John Kerry (D-Mass.), had said Thursday as they left the luncheon: Democrats felt comfortable using the Reid-McConnell agreement going forward.

“We have to know some specificity, and that’s why I’ve thought Reid-McConnell is the best option,” Feinstein said, adding that provisions from the “gang of six” bipartisan budget talks could be added in the future once the debt ceiling was raised.

Kerry said Thursday: “The best thing for us to do is to embrace the McConnell-Reid approach. … It is, in fact, a very specific and very tough process, which the Senate and Congress would have to complete the task of the big deal. So you get the best of both worlds.”

But as reports swirled Thursday and Friday on the contours of the Obama-Boehner deal, Congressional Democrats issued more “no comments” than daggers toward the White House.

Now on the sidelines, many Senators just seemed to shrug as they made preparations to return to their states.

Feinstein, who will stay in D.C. this weekend, seemed to lay down the rank-and-file Democratic party line.

“It’s big stuff,” she said. “You really have to know what you’re doing before blithely saying you’re going to enact it.”

As Reid said, the Senate is waiting.