Washington (CNN) The federal budget deficit ballooned in the first four months of the 2019 fiscal year, growing 77% over the same period a year earlier as tax revenue plummeted and government spending went up.

Figures released Tuesday by the Treasury Department showed the deficit hitting $310 billion, up from $176 billion a year ago.

Treasury said that part of the increase in the deficit was due to a shift in timing of certain payments.

The fresh numbers come as the White House is preparing a new budget for the federal government, which is expected to be released in mid-March, is certain to incite pushback by congressional Democrats.

The growing deficit is being driven in part by the 2017 Republican tax reform , which sharply cut taxes for corporations as well as individuals.

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