WASHINGTON, March 10 (Reuters) – U.S. existing home sales unexpectedly increased in February as lower mortgage rates and a moderation in house-price growth pulled buyers back into the market, but ?still-tight supply could constrain activity during the spring selling season.

The report from the National Association of Realtors on Tuesday offered some glimmers of hope for the housing ?market recovery, with affordability steadily improving. The share of first-time home buyers was the highest in five years. Housing affordability has become a political talking point ahead of the November midterm elections.