The prime minister's party held on to the top spot in the monthly public opinion survey conducted for ERR by TNS Emor, with 31 percent support from decided voters.
The Reform Party's lead has been buoyed ever since the change of government. Its support was 31 percent last month as well, but only 24 percent prior to the change of cabinet in March.
The Reform Party was followed by its partner the Social Democrats (which shed one point) and the opposition Center Party (which stayed the same), tied with 24 percent.
IRL had 16 percent support, up from 14 percent in June.
The survey revealed that undecided voters still make up a large share among those who would be eligible to vote in the 2015 general election - 36 percent, meaning that support for the Reform Party is actually 23 percent.
TNS Emor analyst Aivar Voog attributed Reform's lead to incumbency:
"One reason is certainly that the Reform Party is the prime minister's party and they have more chance to stand out in the media. They seem dominating in the coalition."