Drawn-out negotiations between the White House and Republicans to raise the $31.4 trillion debt ceiling have unnerved markets and fanned worries about the economic impact of a possible default.

Global rating agencies have warned of a downgrade of the country if a deal is not reached soon. Following are some of the actions by the agencies in recent days:

Fitch:

Fitch earlier this week put the U.S. credit rating on watch for a possible downgrade. The agency currently rates the country's debt "AAA" - its highest rank.

Fitch said it still expects the standoff to be resolved before the X-date, the deadline after which the federal government would not have enough finances to meet its payments.

Treasury Secretary Janet Yellen has insisted that the actual X-date is June 1, but some Republicans have questioned that deadline.

Moody's:

The agency expects the U.S. government will continue to pay its debts on time, but public statements from lawmakers during the negotiations could prompt a change in its assessments of the U.S. credit outlook before a potential default.

Moody's currently has an "Aaa" rating for the U.S. government with a stable outlook - its highest creditworthiness evaluation.

S&P Global:

The agency has not put U.S. ratings on watch yet, but has had its second-highest rating on the country since 2011, in contrast to Fitch and Moody's.

That year, S&P took a bold call to cut U.S. rating to "AA-plus" from its highest "AAA" even as a default was narrowly averted.

The agency cited heightened political polarization and insufficient steps to right the nation's fiscal outlook for its decision.

DBRS Morningstar:

On Thursday, DBRS Morningstar put the U.S. on review for a downgrade, warning of the implications of not reaching a deal soon.

Another agency, Scope Ratings, also placed its 'AA' rating for the U.S. under review earlier this month for a possible downgrade due to longer run risks associated with the debt ceiling.

(Reporting by Niket Nishant in Bengaluru; Editing by Sriraj Kalluvila)