WASHINGTON — The Senate has voted to extend for four months the program that provides flood insurance for nearly 5 million homeowners and business owners. The bill’s passage by an 86-12 vote Tuesday averts a scenario where people living in coastal communities would have been unable to renew their flood insurance policies or purchase new ones during the peak of hurricane season. The National Flood Insurance program owes more than $20 billion to the federal treasury. Many lawmakers want to reduce the reliance on taxpayers and are pushing changes that would hike rates for some high-risk properties. But those proposed changes have raised concerns from some lawmakers that flood insurance will become unaffordable for many of their constituents. The extension gives lawmakers more time to work out a compromise.