SACRAMENTO, Calif. (AP) — The federal Government Accountability Office is giving generally good grades to the California High-Speed Rail Authority’s business plan to build a $68 billion bullet train.

In a report given Thursday to members of Congress, the GAO says the authority’s ridership and revenue forecasts are reasonable. It could not assess whether the authority’s projected costs are feasible, but says the California agency is following most of the GAO’s best practices in making its predictions.

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The biggest hurdle remains money. The report says a funding gap of $39 billion is unlikely to be filled by the federal government given the current political climate in Congress.

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Rail officials plan to start work this summer on the first stretch of track and have said they will not start other segments until funding is secured.

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