WASHINGTON — One of Congress’ more obscure priorities — the upkeep of the nation’s infrastructure — has gained urgency in the wake of the Minneapolis bridge collapse. But the job of rebuilding it might be easier for engineers than politicians. On Wednesday, key lawmakers pledged to push for billions of dollars in funding to repair U.S. transportation infrastructure when Congress returns next month from its summer recess. But they will run into plenty of political obstacles. For one, the number of structurally deficient or functionally obsolete bridges — more than 150,000 or about one-fourth of the nation’s bridges — would require an enormous investment: $65 billion, or perhaps more. That’s more than the Department of Homeland Security expects to spend next fiscal year. For another, while lawmakers have pledged to spend more on bridge maintenance, the Democratic-written transportation appropriations bill, even without the additional money, already faces a presidential veto threat in a clash over its cost. An increase in the 18.4-cent-per-gallon federal gasoline tax, a potential funding source, appears to be a non-starter at a time when pump prices are high and an election is looming. And it might be difficult to keep the […]