If you are conservative then there is no reason to justify voting for Barack Obama. His record clearly shows he is one of the most liberal members in Congress. In the General Election he has tried to lean towards the middle--but failed. In his economic policy he wants to "spread the wealth," a very socialistic idea. Aside from that his economic plan doesn't help that many middle class workers like he claims it does. McCain and Obama differ significantly on spending too. Obama wants to increase spending while "lowering taxes" for some and raising them for others. In my mind there is no way we can increase government spending in the state the economy is in right now. McCain on the other hand wants to significantly decrease government spending and not raise taxes. In 2001 one he voted against making the Bush tax cuts permanent because there was no decrease in spending to balance out. He now wants these tax cuts permanent while decreasing spending.
McCain is not afraid to step across party lines. This has angered conservatives sometimes. The country now more than ever needs someone that will be willing to listen to and work with both sides. If Obama is elected there will be a Democrat majority in the House, Senate, and the White House--giving him even less reason to work with conservatives. He also has very little record of stepping across party lines. Why would he change now?
The last point that most people don't think about is the appointments to the Supreme Court. There will most likely be one or two appointments during the next Presidency, If Obama were elected this could shift the courts to a majority liberal also. So conservatives wouldn't have much of a voice anywhere.
I believe that there will be change no matter who is elected. But think about what kind of change you want.
Here is a good article.