As the clock ticks down to the September 30 deadline to fund the US government, lawmakers in Congress are scrambling to reach an agreement on a short-term spending bill to avert a government shutdown.

The Democrat-controlled Senate and the Republican-led House have put forward their respective plans, and a heated debate has emerged, centered on whether to include substantial aid for Ukraine in the funding package.

Republican House Speaker Kevin McCarthy has taken a firm stance against the inclusion of Ukrainian aid worth billions of dollars in a short-term funding bill.

McCarthy asserted that it is "wrong" to prioritize Ukrainian assistance over addressing domestic concerns. "They're picking Ukraine over Americans," McCarthy criticized during a press conference, highlighting his reservations about the Senate's bipartisan government funding proposal.

"If they want to put focus on Ukraine and not focus on the southern border, I think their priorities are backward," McCarthy said, voicing concerns about the Senate's priorities.

The Senate's proposal, known as the Continuing Appropriations Act, aims to fund the federal government until November 17, providing more time for lawmakers to pass comprehensive spending bills.

Notably, the Senate's Continuing Resolution (CR) includes over $6 billion in military and economic aid for Ukraine, a substantial decrease from the $24 billion in funding initially requested by President Joe Biden in August. An additional $6 billion is designated for natural disaster funding.

Notably absent from the Senate's bill is any provision for increased border security, a key point of contention between the two chambers.

While McCarthy stopped short of confirming whether the Senate-passed bill would be put to a vote in the House, he announced his intention to present the House's short-term spending bill, which includes funding for border security, for consideration by Saturday.

McCarthy defended this approach, stating, "I think that's the appropriate way to be able to keep government funding, secure our border, while we continue to keep the government open to work on the rest of the appropriations process."

Additionally, McCarthy indicated that the House's spending measure would adhere to a lower spending level than the $1.59 trillion previously agreed upon during the debt ceiling dispute in May. The lower spending threshold reflects the ongoing debate between the parties over the size and scope of government expenditures.

Race against time

Leaders from both sides of the aisle in Congress have been racing against time to pass a short-term funding extension, aiming to prevent a government shutdown and maintain essential services. However, the success of this plan remains uncertain due to deep-seated divisions over spending priorities and policy disagreements, particularly concerning aid to Ukraine.

Read more: 41% of Americans critical of US aid to Ukraine: Post-ABC poll

Government funding is set to expire at the stroke of midnight on Saturday, September 30, marking the beginning of the new fiscal year on October 1. If Congress fails to enact legislation to renew funding by this deadline, the federal government will cease non-essential operations and services at midnight. The full impact of the shutdown is expected to become evident at the start of the work week on Monday.

In the event of a government shutdown, many federal operations and services will grind to a halt, except for those categorized as essential.

Federal agencies maintain contingency plans that outline which activities will continue and which will be suspended. Critical functions like border protection, federal law enforcement, and air traffic control are expected to carry on.

"If you’re a government worker, it’s highly disruptive — whether you’re not going to work or whether you are," said Maya MacGuineas, president of the Committee for a Responsible Federal Budget, a nonpartisan, nonprofit organization.

"If you're somebody who wants to use one of the services that you can’t get access to … it’s highly disruptive. But for many people … all the things that they are expecting and used to seeing of government are still happening and the inconveniences and the kind of wasted time and wasted resources aren’t things that they see and feel directly."

Read more: Biden warns GOP extremists: Government shutdown a threat to all

The White House, meanwhile, issued a stark warning regarding the potential consequences of a shutdown. The administration estimates that 10,000 children would lose access to Head Start programs (free learning and development services), air traffic controllers and transportation security officers would work without pay, causing travel delays, and food safety inspections by the Food and Drug Administration would also be delayed.