Originally Published: 06 MAR 23 11:40 ET

Updated: 06 MAR 23 13:40 ET

By Jeremy Diamond, Manu Raju, Lauren Fox and Melanie Zanona, CNN

(CNN) -- DC Council Chairman Phil Mendelson on Monday wrote a letter to the Senate attempting to withdraw the district's criminal reform legislation from congressional review after it became clear the Senate intended to nix the legislation.

"This morning, I delivered a letter to the Senate withdrawing the criminal code reform commission legislation," Mendelson said during a news conference on Monday.

"It's clear that Congress is intending to override that legislation and so my letter, just as I transmit bills for their review, withdraws from consideration the review."

Senate leadership aides on both sides are trying to understand the implications of his attempted withdrawal. A senior Republican aide said the GOP still expects a Senate vote this week to halt the local legislation.

Another leadership aide added: "Not only does the statute not allow for a withdrawal of a transmission, but at this point the Senate Republican privileged motion will be acting on the House disapproval resolution, rather than the DC Council's transmission to the Senate. We still expect the vote to occur."

Mendelson's decision comes days before the Senate is set to vote to overturn the crime bill. Legislation to overturn the bill was expected to pass overwhelmingly and President Joe Biden had said he would not veto the effort.

"Pulling it back means the clock stops and would have to be retransmitted to both Houses and that this will enable the council to work on the measure in light of congressional comments and to retransmit," Mendelson said.

Mendelson added that he has "not found precedent" for a DC council chairman withdrawing legislation that has already been submitted to Congress for review, but said he believes he has that authority since the DC Home Rule Act empowers the chairman with transmitting legislation to Congress.

"The Home Rule Act is very clear that I transmit and there is not a prohibition on my pulling it back," Mendelson said. "This law will not go into effect because I have pulled it back."

Still, Mendelson added that he is not certain that this step "will stop the Senate Republicans, but our position stands: The bill is not before Congress any longer."

The DC City Council came to the decision once it became clear that Biden would sign the disapproval resolution, and worked over the weekend over how to execute it, according to a source familiar with the situation.

Council members -- like many Hill Democrats -- were blindsided by Biden's position and received no heads up from the White House, the source added. But once it became clear the law would be overturned, they felt there was no point in keeping it before Congress for review.

The DC City Council received guidance from the Senate parliamentarian, and believes at this point the Senate vote would simply be on the House-passed disapproval resolution, which would be a messaging vote that would have no bearing on whether the DC crime law is actually implemented since it's already been withdrawn.

People who advocated for updating the DC criminal code -- which hasn't been updated since the early 1900s -- are angry that Democrats let Republican "soft on crime" messaging take hold and are upset with both the president and mayor for not fighting for DC's right to govern itself, even if they disagreed with the underlying law. Proponents of the bill fear the episode has undermined the fight for DC statehood.

The upcoming vote has split Senate Democrats, reflecting the delicate balancing act the party faces on the issue of crime. Biden's announcement that he would not veto the measure before Congress angered some in his own party, including progressives who have argued that the district's elected leaders have the right to govern themselves.

Biden's announcement also put moderate Democrats who voted against the Republican proposal more open to political attacks from the GOP for being soft on crime. Some of those moderate Democrats were furious with Biden for waiting to signal his intentions until after they had voted against the effort.

"Cannot trust the White House," one House Democrat who voted for the measure fumed last week.

Biden's announcement opened up the floodgates for multiple Democratic senators to announce they would vote for the measure repealing the DC crime law. Arizona Sen. Mark Kelly told CNN he thinks a lot of his Democratic colleagues "will be voting for it," including him. Pennsylvania Sen. Bob Casey counted himself among that number, though he argued he'd already made his mind up before Biden's announcement. New Mexico Sen. Martin Heinrich said he, too, would vote in favor.

A number of others, including fierce defenders of DC statehood, also said they were still weighing the issue.

This story has been updated with additional reporting.