That's not to say that there's no difference between the two parties -- because there is. That's not to say that the country would be better off if John McCain loses; it most certainly wouldn't be. That's not to say that the Republican Party isn't more conservative than the Democratic Party; without question, it is.
That being said, does the Republican Party adequately represent conservative interests? No. Do George Bush and John McCain's values and beliefs match up well with those of the average conservative in the Party? No, they do not. Does the machinery of the Republican Party -- the RNC, the NRCC, NSCC -- treat conservatives fairly and do a good job of representing conservative interests? Not at all.
In other words, to many conservatives, the Republican Party has ceased to be an organization that serves their interests and has become merely an allied organization that shares many, but not all, of the same critical goals.
That may seem like a small distinction, but it's an important one. Conservatives will stay up late volunteering for a campaign, give until it hurts, and crawl over broken glass to put candidates in Washington who're "on their side."
However, it's a totally different ball game when we're talking about mere allies. Why give money and spend precious time volunteering on the campaigns of people who are going to turn right around and cut you off at the knees on spending and illegal immigration once they get to DC?
In other words, the attitude towards the GOP has become, "He may be a son-of-a-b*tch, but he's my son-of-a-b*tch." That's what today's Republican Party is to most conservatives: our sons-of-b*tches.
........Which brings us, as conversations of this sort usually do, back to Reagan. Why did conservatives love Reagan? Certainly, he was a great President, but he departed from the conservative orthodoxy on more than a few occasions. Reagan signed an abortion bill when he was governor of California, the debt exploded under his watch, he raised taxes, he signed an amnesty bill, and Iran-Contra was certainly a big scandal. Yet conservatives, who were just as serious about their principles back then as they are today, supported him ferociously when he was in office and revere the man's memory.
Simple: because there was never the slightest doubt in the minds of conservatives that Ronald Reagan shared their values and was doing everything within his power to use conservative principles to make our country a better place. So, when Reagan did something that conservatives disagreed with, they figured he was just doing what he had to do for the sake of politics and didn't hold it against him.
Republicans today don't have that luxury because the assumptions that conservatives made about Reagan have been reversed. If a Republican does something that pleases conservatives, they often assume that it is being done for political purposes while deviations from the conservative norm represent what Republicans really want to do.
Until the Republicans can repair that breach of faith and convince conservatives that the GOP has the same goals as conservatives do on issues like spending, the size of government, and illegal immigration, the Party may win some battles, but it's going to slowly, but surely lose the war for the future of our country.