The Liberal government is rejecting the Senate’s major changes to Bill C-46, the government’s impaired driving framework meant to accompany cannabis legalization.

The government says it rejects the key change that stripped mandatory alcohol screening from the bill because it is a “proven traffic safety measure that will deter impaired driving and save lives,” according to the response message to the Senate placed on the House of Commons notice paper.

It’s also rejecting immigration-related amendments the Senate made to the bill that stated impaired driving convictions would not qualify as “serious criminality.” That was done to prevent permanent residents and foreign nationals from becoming inadmissible to Canada after receiving convictions.

The message states that change is being rejected because it “indirectly amends the immigration legal framework through a criminal law statute and would treat impaired driving offences differently from other serious criminal offences.”

The Senate adopted the bill at third reading last week on division after it removed the mandatory screening provisions, which the justice minister had called the “centrepiece” of the legislation. A bid to put the screening provisions back into the bill at third reading failed in the Senate chamber last week on a tie vote.

Opponents of mandatory alcohol screening, which would allow police to take a breath sample from drivers they pull over without having reasonable suspicion of impairment, argue that it’s unconstitutional. The government contests that.

The House of Commons will soon debate the government’s motion and the two chambers will have to agree on what to do with the controversial measures before the bill passes into law.

With the House of Commons scheduled to rise at the end of the week, the parliamentary calendar is ticking on and it’s possible the bill could run down the clock.

The federal government had originally stated that it wants to have elements of Bill C-46 that address drug-impaired driving in force before Bill C-45, the Liberal government’s cannabis legalization bill, comes into force. But parliamentary secretary Bill Blair told CBC News in May that any delay in Bill C-46 is “not an impediment to the passage and implementation of Bill C-45.”

Last week, Prime Minister Justin Trudeau accused the Conservatives of playing “games” with his cannabis legalization agenda in the Senate to slow things down. But the Conservatives disagree, and say it’s the Liberals who control the pace of legislation in both chambers.