A state senator facing a competitive reelection bid this fall has proposed legislation that would make his district more Republican — and therefore safer for him.

Sen. Bryce E. Reeves, a freshman senator from Spotsylvania County, about an hour south of the District, won his seat four years ago by 226 votes. He already faces a Democratic challenger this year.

Reeves filed a bill that would trade precincts with a neighboring district represented by Sen. R. Creigh Deeds (D), giving Deeds a heavily Democratic precinct and taking for himself a Republican one.

Reeves said the bill was not intended to give him a political advantage but to unite two split precincts — which it would do — in order to eliminate confusion for voters and simplify the process for election officials.

“Because of the way the district is designed, there is no perfect plan,” he said. “There are about five different ways to split the child, so that’s the plan I came up with.”

Deeds, who voted against the bill despite the advantage it would give him, said the bill is a politically motivated, unconstitutional attempt to shift entire precincts.

“When you’re flipping a Democratic precinct into the district I represent, and a Republican precinct into the district he represents, how else can you see it?”

On Tuesday, the overwhelmingly Republican House passed the bill, 65 to 33. The Senate passed it, 21 to 18, last month. Gov. Terry McAuliffe (D) has vetoed similar bills in the past but has taken no official position on Reeves’s bill.

Every decade, the General Assembly redraws legislative district boundaries to conform with the U.S. Census. Between redistricting years, lawmakers submit bills that make what they call “technical amendments” to the maps.

The bills often raise eyebrows because of the partisan nature of redistricting. Over the years, maps have been drawn to protect incumbents with heavy concentrations of Democrats and Republicans intended to protect longtime lawmakers from election challenges.

That process, in turn, tends to attract candidates who appeal to the extremes of their parties. Where a district is heavily Republican, a more conservative candidate is more likely to win than in an evenly divided district; similarly, a deeply blue district is more likely to elect a very liberal Democrat.

Advocates for nonpartisan redistricting regularly blame the process for the gridlock and polarization that has increased in recent years in Richmond.

In 2013, Senate Republicans took advantage of the absence of then-Sen. Henry L. Marsh III, who was attending President Obama’s inauguration, to pass “technical amendments” that could have handed the GOP control of that chamber for decades.

House Speaker William J. Howell (R-Stafford) killed the map, but ever since, Democrats have ramped up their opposition to such amendments.

After the 2011 statewide redistricting, Jake Washburn, the registrar in Albemarle County, the locality that would be affected by Reeves’s bill, said he asked all lawmakers representing the county to try to unify split districts.

But he had nothing to do with Reeves’s new bill, he said.

Jim Heilman, a former Albemarle registrar, said the local electoral board, of which he is a member, unanimously decided to take no position on the bill.

“We considered it essentially political,” he said.

An ideal Senate district should have no more than 2 percent more or less than 200,026 voters. Reeves’s bill could unify two split districts without violating that guideline, yet it goes further — swapping two other precincts to shore up the districts of Reeves and Deeds.

“It is gerrymandering in an election year,” said Traci Dippert, the Democrat challenging Reeves. “He’s trying to make it where the legislator picks his voters, where it’s truly the voters who pick their legislator.”

Reeves, who unseated longtime Democratic incumbent Edd Houck four years ago, said Democrats used the same tactic when they were in charge of the Senate, which is now in GOP hands by a one-seat margin. Reeves noted that Deeds declined to work with him on a compromise bill.

“When I ask for help, I don’t get any help on it,” he said. “We’ve done technical adjustments in the past, when Democrats were in control, and now that they’re not in control, they’re not going to agree to it.”

Earlier in the session, Reeves voted “yes” on four Senate proposals intended to reduce the influence of politics on redistricting.

Anna Scholl, executive director of Progress Virginia, said: “It’s incredibly hypocritical to be publicly endorsing a nonpartisan, nonpolitical process to draw election maps while at the same time exploiting the process to rig his own election before that happens.”