Updated 4:25 p.m. | The Senate will have one more fiscal standoff before leaving for the August recess in what will be an early test of Minority Leader Mitch McConnell’s ability to hold the line on spending this fall.

It’s been a rough road for the Transportation-HUD spending bill that’s the vehicle for that debate.

Missouri Republican Roy Blunt criticized the decision by Majority Leader Harry Reid to move the THUD bill first, rather than starting with a bill like the Military Construction-VA measure, on which Democrats and Republicans could more easily agree.

“I believe if I’d have been the majority leader, I would have picked one of the bills that Republicans are more in line with Democrats on because … the House and Senate number[s] are fairly close together. This is not one of them,” Blunt said. “That’s a decision that the majority leader makes and he may have been looking for a fight, and if he was, he may have gotten one.”

Sen. Patty Murray of Washington, the chairwoman of both the Budget Committee and the Subcommittee on Transportation-HUD, has run point for Democrats. “I know there are those in the Republican leadership that are working very hard now to not allow this bill to be finished,” Murray said Wednesday. “We are hoping that our Republican colleagues will join us tomorrow to make sure that we are making the right investments, that we are not managing by crisis, but doing the job that we were sent here to do.”

McConnell announced Wednesday morning on the Senate floor that he was encouraging opposition to the bill, which should come as no surprise since the Kentucky Republican has voted against the measure in committee, where he has maintained his seat.

“Voting for appropriations legislation that blatantly violates budget reforms already agreed to by both parties moves our country in the exact wrong direction. It puts us on the Democrat path to austerity. That’s one of the many reasons I’ll be voting against this spending bill, and that I urge my colleagues to do the same. Because it’s time to get serious about the challenges we face,” McConnell said. “It’s time to work together to reposition America for growth, and prosperity, and sustainability in the 21st century.”

The real suspense is whether 40 Republicans will join McConnell in opposition, a move that could be a proxy for the top-line spending levels in a stopgap spending bill come September. He seemed likely to win that fight Wednesday.

Senate Appropriations Chairwoman Barbara A. Mikulski, D-Md., has been writing bills drafted at a $1.058 trillion spending level for fiscal 2014, as opposed to the $967 billion favored by Republicans. The GOP level would adhere to the sequester-mandated level, but Democrats and some Republicans want to roll back all or parts of the automatic spending cuts.

Sen. Lamar Alexander, R-Tenn., a member of the Appropriations panel, said that he hadn’t made a decision on how to vote on the procedural motion. “Some feel that we should go further through the process. Others feel that it’s just misleading people,” Alexander said. “You’ve seen different Republicans cast different kinds of votes in the Appropriations Committee, and that seems confusing, but it’s not really because in the end, all of us have said we’re not going to vote for more than $967 billion unless we find entitlement savings to move over to discretionary spending.”

“The reality is that Republicans and Democrats both drive on roads. Republicans and Democrats care about whether or not the bridge they’re driving over is safe, and this should not be a partisan issue,” Stabenow said.

“I’m hopeful that some of our Republican colleagues will realize that the continued mindless cuts of middle-class bread and butter, as exemplified by [McConnell’s] comment that we should just continue to cut the THUD bill, will be rejected by some of our Republican colleagues,” Schumer said. “I don’t know if that’ll happen, but I hope it will.”

When Reid tried to get an agreement locked in on a batch of amendments before the floor closed for business, Sen. Susan Collins, R-Maine, offered a reluctant objection.

Collins, the ranking member on the Transportation-HUD panel, has worked with Murray to advance the measure. Stabenow praised those efforts Wednesday morning.

However, it remained entirely unclear whether the bill could achieve the 60 votes needed to cut off debate.

“We need to hold together and defeat cloture on the bill,” Republican Conference Chairman John Thune of South Dakota said Tuesday.

Some Republican appropriators who might be inclined to support the procedural vote demurred when asked about their own views. For instance, Mississippi Republican Thad Cochran would only say that he would review the arguments for and against the bill.

Sen. Richard C. Shelby of Alabama, the top Republican on the Appropriations Committee, has voted against all of the regular bills throughout the process, but some GOP senators have defected and voted in support of the bills at each step.

Still, the Senate’s on track for an August recess getaway as early as Thursday. Tuesday brought the confirmation of a full slate of nominees to the National Labor Relations Board, a key part of the deal brokered by senators to avoid the “nuclear option.”

The chamber has a few nominations and legislative matters to process that typically get cleared away before the recess period by unanimous consent. In addition, Reid may take the procedural steps needed to get a bipartisan energy efficiency bill in the queue for the fall. After that, senators are expected to leave town until September, when the battle over Transportation-HUD spending will expand to all appropriated funds, leading up to a potential government shutdown showdown approaching Oct. 1.

Kerry Young contributed to this report.