I am certain of one thing: both have good reputations but one of them will be wrong. I'll summarize their arguments. Writing for National Journal, Cook begins with an overview:
For Democrats, the good news is that there doesn't appear to be an overwhelming Republican tide this year; the bad news is that Democrats could well lose the Senate even without such a wave. Six of the most competitive races are Democratic-held seats in states that Mitt Romney carried by 14 points or more. With a map like that, Republicans don't need to dominate the country.And Cook concludes:
That leaves no fewer than nine very close races, at least half of them headed toward photo finishes. But three Democratic-held seats are already gone, and party strategists see seven more teetering on the edge, compared with just two for Republicans. Given that equation, you'd have to bet on the GOP.Now let's look at Jay Cost's argument for The Weekly Standard. Cost notes that the circumstances in today very closely mirror those at this date in 2010 - a GOP wave year.
If we dig a little deeper, what we see is a notable improvement in quality from 2010 to 2014. First, candidate recruitment favors the Republicans this time around. (snip) Second, the playing field is much more favorable to Republicans this year than in 2010.And Cost concludes:
Weighing in favor of a 2010 repeat is the relative weakness of President Obama. At this point in 2010, his job approval rating in the Real Clear Politics polling average was 46 percent; today, it is 42 percent. That decline in approval is matched by an increase in disapproval, from 47 percent to 52 percent. On the other hand, the Republican party’s reputation has seen a similar decline.
This year, Republicans should do not only well, but very well. If they don’t, it will be the surest sign yet that something is very wrong with the Grand Old Party.COTTonLINE concludes that there are many things wrong with both major parties, as always. That is unlikely to change given that each party tries to represent the interests of a majority of American voters - a very diverse collection of groups with competing interests.