Gov. Dannel P. Malloy on Wednesday refused for a second time to extend Connecticut’s manufacturing apprenticeship tax credit. The governor said the expansion would create a revenue shortfall of $650,000 unaccounted for in the bipartisan state budget. Those supporting the tax-credit expansion during the legislative season argued the apprenticeship program has helped reduce the manufacturing labor shortage, where an estimated 3.5 million U.S. manufacturing jobs were unfilled in 2017, according to government data. But Malloy said the U.S. Department of Treasury has said that only 10 percent of pass-through entities are small businesses, while large businesses have garnered rate cuts and increased deductions from a Republican-controlled Congress.