PHOENIX (AP) _ George Bush has expanded his lead over Michael Dukakis in Arizona, according to a new poll that shows the Republican presidential nominee doubling the margin he held over his Democratic rival in June.

According to the poll, conducted by The Arizona Republic following last week's vice presidential debate, Bush leads Dukakis 54-34 percent with 12 percent undecided. In June, Bush led a similar Republic poll 47 percent to 37 percent.

In addition, the degree of support for Bush was stronger in the current poll than for Dukakis. Three of every five Bush supporters said they favored him strongly, while the Dukakis camp was evenly split between strong and moderate supporters.

The Republic poll, published in Thursday's editions, is based on telephone interviews conducted Oct. 6-9 with 808 randomly selected registered voters. Of those surveyed, 301 said they are registered Democrats and 397 described themselves as registered Republicans.

The margin of error was plus or minus five percentage points for Republicans and plus or minus six percentage points for Democrats.