Top Democrats are expected to dare Republicans to block a stopgap funding measure, which would trigger the double-barreled fiscal crisis of the US defaulting on its mammoth debt and a shutdown of the federal government, according to two sources familiar with the proposal.

The plan being considered by the House speaker, Nancy Pelosi, and the Senate majority leader, Chuck Schumer, involves suspending the debt ceiling past the 2022 midterm elections in a stopgap bill that would keep the government funded through early December, the sources said.

Democrats want to then dare Republicans to block the stopgap funding measure with a filibuster and prevent it from receiving 60 votes needed to pass the Senate – which could cause a government shutdown on 1 October and leave the US unable to pay its bills.

But economists say a failure to raise or suspend the debt limit when tied to the stopgap funding measure would be particularly catastrophic as the US would be unable to service its debt obligations in the midst of a potentially non-functional federal government.

The strategy to tie the potentially catastrophic prospect of the US defaulting on its $28tn of debt with a government shutdown could put Republicans in a difficult position after their repeated refusal to raise the debt limit in a bipartisan fashion.

Instead, top Democrats are moving forward with a plan to add such language in the stopgap funding measure that would keep the government funded through either 3 December or 10 December, the sources said, and hope to persuade 10 Senate Republicans to support the bill.