CHICAGO (Reuters) - Illinois’ Republican governor has launched an unusual attack ad in his re-election campaign that features three neighboring governors crediting their states’ job gains to Illinois taxes crafted by a state House Democratic leader. Illinois Republican Governor Bruce Rauner, who kicked off his 2018 re-election campaign this week, saw his first term marred by a political impasse that left Illinois without a budget for two years before lawmakers overrode his veto this summer to raise taxes.     Governors in the new ad include Missouri’s Eric Greitens, Wisconsin’s Scott Walker and Indiana’s Eric Holcomb - all Republicans like Rauner - thanking Rauner’s political foil, Illinois House Speaker Michael Madigan, for blocking reforms, raising taxes and sending jobs to their states. “Hoosiers love you, Mike Madigan,” Holcomb said in the ad. Among the Democrats whom Rauner, a wealthy businessman, could face after a March primary are J.B. Pritzker, an heir to the Hyatt Hotels Corp fortune, and Chris Kennedy, son of the late U.S. Senator Robert Kennedy.        The governor’s race in the fifth-largest state is expected to rank among the most expensive in the country. Experts who follow elections said the ad was unusual. “This is creative since it uses GOP governors from surrounding states to shift the blame for Illinois’ woes from Rauner to a Democratic leader,” University of Virginia political science professor Larry Sabato said.  “Voters usually hold their governor responsible for the state of the state,” he added.  While it is not unusual for governors to make appearances for other campaigns, they tend to take a more positive approach, highlighting an incumbent’s achievements, said Dick Simpson, a political science professor at the University of Illinois at Chicago.     While the ad may resonate with rural, conservative voters, it also comes as Illinois and other states seek to attract Amazon.com’s $5 billion second headquarters. Simpson said highlighting how Illinois policies hurt the state is “probably not helpful.”     Madigan dismissed the ad in a statement, calling it a “race to the bottom being led by his role models from states where middle-class wages are a fraction of what they are in Illinois.”     Rauner has feuded with Democrats, who control the state legislature, over his insistence a state budget be tied to policy demands that would weaken unions, impose legislative term limits and freeze property taxes.     He also has angered conservatives by signing a bill to expand state-funded coverage of abortions. Political scientists said he faces a tough re-election bid in a state often carried by the Democratic candidate in presidential elections. Spending on the race could top $150 million, a rarity, said Sarah Brune, executive director of the Illinois Campaign for Political Reform. 