For years, Republicans have warned about the government’s reliance on borrowed money to pay its bills. That stance has often led to standoffs over raising the nation’s borrowing cap, with Republicans insisting that any increase in America’s so-called debt limit be paired with spending reductions.

This year, the party of fiscal conservatism is poised to discard that philosophy as Republicans prepare to press ahead with domestic policy legislation that combines nearly $4 trillion in tax cuts with a $5 trillion increase to the debt limit. An increase of that magnitude would be a record and underscore the ideological flexibility that many Republicans are willing to embrace when they are in power.

G.O.P. lawmakers are prepared to push through the debt limit increase with only votes from their party, through a budget process called reconciliation. That is making it harder for Republicans to maintain their fiscal hawk credibility, prompting some resistance from a few lawmakers who have warned that they may not vote for the bill if it includes such a large increase in the borrowing cap.

The national debt is approaching $37 trillion. This week, Senate Republicans unveiled legislation that would raise the debt limit by $5.1 trillion, higher than the $4 trillion increase that House Republicans voted for in their bill last month. Such an increase would likely extend the nation’s ability to borrow into 2028.

Most economists and analysts welcome a reprieve from debt limit brinkmanship that has destabilized the economy in recent years. However, raising the debt limit along with legislation that is projected to add $3 trillion to the national debt over a decade suggests that lawmakers are overlooking the nation’s long-term fiscal problems.

“The most stunning thing is that this massive debt-ceiling increase would be paired with a massive increase in new borrowing, whereas in the past the pressure has been to couple them with debt decreases,” said Maya MacGuineas the president of the bipartisan Committee for a Responsible Federal Budget.