House Republicans are delaying the release of their tax reform plan after failing to finalize last-minute changes to the legislation, multiple sources told Fox News Tuesday.

The details of the plan were to be unveiled on Wednesday, but the sources said that was now being delayed until Thursday. House Ways and Means Committee Chairman Rep. Kevin Brady, R-Texas, had promised as recently as 4 p.m. ET Tuesday that the bill would be rolled out Wednesday.

However, Brady said the committee would “work through the night” on the bill, but would not say whether the planned release was still on for Wednesday. When asked about the timing, a senior committee source said, “we’ll keep you posted.”

The committee had worked throughout the day and evening to produce a plan for the first overhaul of the nation’s tax code in three decades.

Although they had settled on some key details — such as a cut in the corporate tax rate to 20 percent and maintaining the top personal income tax rate for the wealthy of 39.6 percent — other elements still had to be resolved.

Late Tuesday, reporters in the hall outside the committee’s office could hear raised voices as members appeared to be arguing.

Trump has intensified his lobbying for the nearly $6 trillion tax overhaul plan, seeking a major legislative achievement after the collapse of the health care repeal. The president predicted a grand signing ceremony before Christmas at “the biggest tax event in the history of our country.”

The plan originally unveiled by Trump and congressional Republicans called for shrinking the number of tax brackets from seven to three, with respective tax rates of 12 percent, 25 percent, 35 percent. That plan drew immediate criticism from Democrats, who complained it was too favorable to the wealthy and undermined Trump’s rhetoric about it benefiting the middle class.

Fox News’ Chad Pergram and The Associated Press contributed to this report.