Jan. 9 (UPI) -- Another Republican seat in Congress will be up for grabs in this fall's midterm elections.
California Rep. Ed Royce announced Monday he won't seek re-election, leaving his district vulnerable to a potential party change in November.
Royce, who's served in the House for 25 years, surprised party leaders when they learned of the 13-term congressman's decision to retire.
The Southern California representative said he wanted to concentrate on his final year as House Foreign Affairs Committee chairman.
Royce, 66, who represents parts of Los Angeles, Orange and San Bernardino Counties, said he plans to focus on "urgent threats facing our nation" -- including "brutal, corrupt and dangerous regimes" in North Korea and Iran. He also said Russian President Vladimir Putin's "continued efforts to weaponize information to fracture western democracies" and "growing threats in Africa and Central Asia" are top priority issues.
Royce's decision to retire adds to a growing list of opening Republican congressional seats. In order to take control the House, Democrats need to gain 24 seats in November.
So far, 28 Republicans and 14 Democrats have announced they are leaving their House seats after this year. Special elections to fill four open congressional seats in Michigan, Ohio, Pennsylvania and Arizona will be held before the Nov. 6 vote.
Royce's Orange County district is now considered vulnerable in the midterm elections.
In 2016, the district backed Hillary Clinton for president by 8 percentage points. After Royce announced his retirement, David Wasserman, editor of the nonpartisan election predictor The Cook Political Report, moved the district from its "lean Republican" category to "lean Democratic."