Rush Limbaugh has stated that a McCain nomination would ruin the Republican Party. This is only partially right. McCain's recent success is indicative of (and a McCain nomination would merely confirm) the reality that the Republican Party is already ruined.
For the last several years, the GOP machine seems to have adopted the misguided attitude that the Reagan-Conservative movement is the ugly stepchild of the party - rather than being the party's true heart, soul, and core. The party is happy to accept their support, but won't actively pursue their interests. Evangelicals and their values are especially marginalized and vilified. The elephant is still in the living room, but is unspoken of. Instead, the RINO seems to have been moved to the forefront. Reagan's name is frequently invoked... but his philosophies and policies are rarely emulated.
Last summer, Republican Senators had to be dragged kicking and screaming into killing the McCain/Kennedy Amnesty Bill. Many were seemingly hiding under their desks as their phone lines melted down. Some would not take a public position on the subject until the writing of the bill's defeat was already on the wall.
A revolution is coming. The Conservative Core is tired of holding their nose while casting votes for nominal Republicans who do not represent a Reagan-Conservative viewpoint. The so-called "Neo-Conservatives" have sorely disappointed the Reagan-Conservative base. Spending, border security, amnesty, etc., have all been poorly handled by Republicans both currently and recently in office, in the eyes of the Reagan Coalition. This dissatisfaction became quite evident in the mass "firings" of Republicans in 2006. The 2006 elections were not a repudiation of conservative thought; they reflected the disappointment of conservatives with Republicans' failure to represent them.
The approval ratings for Congress since the 2006 elections have ranged from a high of 25% to a low of 11%, and have consistently rated below the approval ratings of the supposedly hated President George W. Bush. If the Democrats swept into office in 2006 because they had some mandate for their policies, why are their approval ratings tanking?
But now comes John McCain: anointed by the mainstream press as the heir apparent to the Republican nomination, and endorsed by the old gray mare herself, the NY Times.
Memories seem to be short... McCain/Feingold was an assault on free speech. McCain/Kennedy was an attempt to ram amnesty down America's throat. McCain opposed the Bush Tax Cuts. McCain has been a frequent obstacle to funding needed military modernization.
Yet "electability" seems to trump the issues. (Who says Obama or Hillary can't be beat by a conservative?) Some in the GOP argue that differences with McCain's positions should be subordinate to party loyalty. "Don't you want a Republican in the White House? Do you want to elect a Democrat?"
If the choice is between McCain and Hillary or McCain and Obama, there is no Republican running. McCain is a donkey in an elephant suit. Electing McCain is like electing a Democrat, with the added risk of putting the blame for any of his detrimental actions as President squarely on the GOP. At least if those same actions are taken by Hillary or Barack, the Dems would have to take responsibility.
Worse for the GOP, a McCain nomination would result in many of the Conservative Core being unable/unwilling to hold their nose and "pull the lever" for McCain. This could mean that many will sit out the election - and this would mean many Congressional and Senate seats and Governorships might fall to the Democrats.
This eventuality must be strongly spoken out against - even if a voter can't find a candidate to support in the Presidential race, they should absolutely get to the polls and vote their consciences in the non-presidential races.
McCain will indeed be the ruination of the GOP. Conservatives are already fleeing the party. Funding of the party machine will dry up. The RNC has received many letters from former supporters saying no more money is forthcoming. If the GOP doesn't wake up and move right, they may find themselves left.