A new internal poll from a Democratic super PAC shows Evan Bayh still holds a big lead in his Indiana Senate race — a week after at least one public survey suggested his lead was smaller than many expected. 

The poll, conducted by the Democratic political firm Global Strategy Group for the Senate Majority PAC, found the Democratic Senate candidate leading Republican Rep. Todd Young by 18 points, 54 percent to 36 percent. 

The survey included 801 likely voters, and was conducted from Aug. 10 to Aug. 14. The margin of error was 3.5 percentage points. 

Like all internal polls, it should be met with skepticism. Last week, a Monmouth University poll found Bayh leading by 7 points, 48 percent to 41 percent. 

The Senate Majority PAC’s findings, in fact, suggest that the former Indiana governor’s advantage is shrinking as the campaign against him wears on: Earlier in August, the Democratic Senatorial Campaign Committee found Bayh leading Young by 26 points. 

Republicans and allied outside groups have spent millions of dollars in TV ads targeting Bayh, who they argue has lost touch with his home state after leaving the Senate in 2011. 

But Democrats are adamant that the longtime veteran of Indiana politics has a significant advantage over  Young, thanks to his universal name recognition in the state and his strong ties to Hoosier voters. In the poll, 40 percent of Republicans say they think favorably of Bayh, compared to just 36 percent who don’t 

Democrats in Washington are counting on the Indiana race as a key part of their plan to win the majority in the Senate this year.

Contact Roarty at alexroarty@cqrollcall.com and follow him on Twitter @Alex_Roarty.