WASHINGTON (Reuters) - The U.S. government will have to stop borrowing money between July and December if Washington doesn't agree to raise a legal restriction on public debt, the Treasury Department said on Wednesday.

Hitting that so-called "debt ceiling" could trigger a U.S. default on its debt and an immediate recession, a risk that has become a regular facet of U.S. politics over the last decade.

The current debt limit was set in March. Treasury has been able to continue borrowing from investors by using accounting measures such as limiting government payments to public sector retirement funds.

"Treasury expects that the extraordinary measures will be exhausted sometime in the second half of 2019," Treasury Deputy Assistant Secretary Brian Smith said in a statement announcing the department's quarterly debt issuance plans.

Wall Street also sees Treasury exhausting its borrowing authority in the third or fourth quarter, according to the minutes of a meeting of a Treasury advisory committee of financiers.

The debt ceiling is already affecting how the government funds itself. Issuance of Treasury bills - short-term debt - is expected to gradually decline over the second quarter due to debt ceiling constraints, Smith said.