WASHINGTON (Reuters) – The U.S. Chamber of Commerce on Tuesday urged Congress to take action on a number of issues before ending work for the year, including preventing a potential rail strike and extending a deadline for the Boeing 737 MAX 7 and 10 to get certified. The largest U.S. business group noted that three rail unions have rejected a rail contract. “A rail strike would be catastrophic for our economy, costing $2 billion per day and imposing enormous challenges to businesses, local communities, and commuters,” the Chamber letter said. The Chamber also backed Boeing efforts to seek a wa…