WASHINGTON, March 19 (Reuters) - The average rate on the popular U.S. 30-year fixed-rate mortgage surged to a three-month high this week as war in the Middle East stoked inflation fears, dealing a blow to the Trump administration's efforts to make housing more affordable.

The 30-year fixed mortgage rate averaged 6.22%, highest since early December, up from 6.11% last week, mortgage finance agency Freddie Mac said on Thursday. Rising mortgage rates, if sustained, could hamper home sales during the typically busy spring season. 

The benchmark rate fell to 5.98% on the eve of the U.S.-Israeli war with Iran after President Donald Trump ordered Freddie Mac and Fannie Mae to expand purchases of mortgage-backed securities. 

It reversed course as the conflict drove up oil prices and U.S. Treasury yields. Mortgage rates track the benchmark 10-year Treasury yield. Housing affordability has become ⁠an increasingly potent political issue ahead of the November midterm elections.