Perhaps. He had to do a lot of flanking in order to make progress which slowed him down. I have no doubt there was time pressure, especially after Grant failed to get to Richmond quickly.
There was obviously pressure, but there was very little chance of McClellan ever winning. He openly repudiated his party’s platform - primarily because the idea of the man who created the Army of the Potomac essentially surrendering that Army when it was near victory was just a disgraceful thought. McClellan was a complicated man, but he did have honor, and he did love his Army - even if he never quite seemed to know what to do with it.
To me, the fascinating part of the Election of 1864 is that the Army voted for Lincoln in numbers that vastly exceeded the rest of the population.