Washington ? A new poll shows Republican Sen. Jim Talent with a slight lead over Democratic challenger Claire McCaskill among likely voters in Missouri’s U.S. Senate race.

The USA Today/Gallup poll released Friday showed Talent favored by 50 percent of likely voters, compared with 44 percent for McCaskill. The margin of error was plus or minus 5 percentage points.

The poll showed the candidates tied among registered voters. The statewide survey of 574 voters was conducted Aug. 23-27.

A St. Louis Post-Dispatch/ KMOV-TV poll in late June showed McCaskill with a 6-point lead over Talent among likely voters. Since then, Talent launched a statewide TV advertising campaign in late July that portrays him as a lawmaker who reaches across party lines to get things done.

Lloyd Smith, Talent’s senior campaign adviser, said the latest poll shows the advertising message is reaching voters.

“This poll is a snapshot in time, and there will likely be polls that show us up and polls that show us down, but this is obviously a reflection of the hard work of Senator Talent and his campaign team over the last few weeks,” Smith said.

McCaskill spokeswoman Adrianne Marsh also called the poll good news because it shows the candidates tied among registered voters despite Talent’s ad blitz.

“For weeks on end, we’ve seen the result of a $2.5 million ad campaign by Senator Talent and the Republican-leaning U.S. Chamber of Commerce,” Marsh said. “It shows that we’re still dead even among registered voters. This shows their spin isn’t working.”