Senate Majority Leader Mitch McConnell and Majority Whip John Thune are trying to win over undecided rank-and-file senators to avoid a replay of last week’s effort in the House, when roughly two-thirds of House Republicans opposed the deal, according to multiple senators and aides.

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McConnell delivered a firm message to his caucus on Tuesday during lunch at the National Republican Senatorial Committee, warning them they cannot leave town until the budget and looming debt ceiling deadline has been addressed, according to three sources familiar with the meeting. McConnell also said the chamber will not recess without passing something.

McConnell and Thune’s goal is to get at least 27 of the caucus’ 53 members to support the deal, a majority of the Republican-controlled Senate that would combine with most of the Democratic Caucus to push the deal over the top. That Republican number may be aspirational given the party’s antipathy for new spending, but Thune said he was “hopeful” he could meet it.

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GOP leaders believe that a significant bloc of Senate Democrats, including those running for president, will not support the deal. That would require even more GOP votes to handily pass the budget deal. The deal requires 60 votes to pass the Senate.

Asked about the level of support in his party, McConnell would say only that the budget deal “will have to pass this week.” The Senate is scheduled to leave for a month-long recess at the end of the week.