House Republicans on Wednesday were still short of the 218 GOP votes they need to guarantee passage of their $659 billion border package.

In his first big test since ascending to No. 3 GOP leadership position, Majority Whip Steve Scalise, R-La., had made solid progress toward assembling sufficient Republican support behind the measure late Wednesday.

Stalwart conservatives such as Rep. Raul Labrador, R-Idaho, and Rep. Cynthia Lummis, R-Wyo., were leaning toward supporting the bill, while Rep. Rob Woodall, R-Ga., the interim chairman of the conservative Republican Study Committee, said he was a firm “yes.”

But Republican sources, while remaining optimistic that the votes would be there when the legislation comes up for a vote on Thursday, said Scalise and his newly installed whip team were trying to overcome a final roadblock of members who were “leaning no.”

The support of these members is needed to ensure a comfortable margin of votes exists for the border bill given that few House Democrats can be counted on to back it.

“It’s going to be close — really close,” a House Republican source said.

Sources familiar with the whip count declined Wednesday evening to disclose how short Republicans were and emphasized that the situation was fluid.

They characterized support for the bill as largely positive and said getting to 218 was about convincing a last group of members of the legislation’s merits and the need for House Republicans to address the crisis of unaccompanied minors streaming across the southern border with Mexico before they adjourn Thursday for a scheduled five-week summer break.

The whip team’s momentum, they emphasized, had not reversed nor was banked support falling off.

The issue that appeared to be causing the biggest problem with the hold-outs was a desire to include language that would overturn the Deferred Action for Childhood Arrivals executive order issued by President Obama two years ago.

The order halted deportations of a certain segment of minors who were brought to the U.S. illegally by their parents.

However, GOP sources said that adding a DACA provision to the border bill would cost Republicans as many votes as it attracted — possibly more.

Even Republicans who support overturning DACA as a matter of policy suggested that it could be a nonstarter because it could be interpreted as a poison pill that would make the House border bill near impossible for Senate Democrats to consider voting for. House Republican leaders want to put political pressure on Obama and the Democratic Senate to consider their bill.

“I think the issue is whether there will be provisions added to get votes, not provisions added that would diminish the bill,” House Rules Committee Chairman Pete Sessions, R-Texas, said. “There is an equal balance to this. We are trying to present a bill to entice the United States Senate to view what we did as very rational and reasonable.”

Immigration issues are always politically delicate for congressional Republicans, and the House GOP majority over the past few years has periodically had difficulty unifying on major legislation. Often times, Republican leaders have had to pull a bill from consideration at the last minute after failing to secure enough GOP votes to pass it.

But support for the border package was holding among Republicans, including those affiliated with the Tea Party, that usually oppose leadership driven legislation.

Despite Obama’s vow to veto the package and Senate Majority Leader Harry Reid’s threat to amend the bill to add the Senate’s “gang of eight” comprehensive immigration reform legislation, these Republicans were sticking with the House GOP bill.

They lauded it for being narrowly targeted to address a problem that requires congressional action.

“I think it’s a good piece of legislation,” Labrador told reporters. “It doesn’t have all the solutions to our border crisis. But it has some really important solutions and it actually addresses the problem we have with the unaccompanied children that would be returned if this law passed.”

Chief Congressional Correspondent Susan Ferrechio contributed to this report.