These days our political parties are defined by their presidents. Their policies and their programs tend to become their party's orthodoxies.
And the perceived success or failure of those policies and programs tends to determine how the party's candidates, even those who don't support many of them, do at the polls.
This has been especially true in the past two decades, in which fewer Americans have been splitting their tickets or changing their minds from election to election than was the case from the 1950s to the 1980s.
For years white Southerners voted Republican or third party in presidential elections and Democratic in congressional and state contests. Now they're solidly Republican.
For most of the 20th century, New York was a target state in just about every election, and Vermont was the most Republican state in the nation. Now they're both hugely Democratic.
These are things to keep in mind as the political air swirls with talk of Barack Obama as a Democratic Ronald Reagan annihilating the Republican Party.
Neither of our two political parties is going to be annihilated. Both have suffered far worse defeats than Mitt Romney and the Republicans suffered in 2012.
Both have figured out how to adapt and win over voters who used to vote against them. Or at least to position themselves to win when the other side's president is seen to have massively failed.
The 2008-2012 Obama campaign -- it never really stopped -- did an excellent job of turning out just enough voters to win 332 electoral votes. But Obama carried just 26 states to Mitt Romney's 24, which is relevant when you look at future Senate elections.
As for House elections, Obama carried only 207 congressional districts to Romney's 228. That's partly because Republicans had the advantage in redistricting after the 2010 census.
But it's also because the Obama core constituencies -- blacks, Hispanics, gentry liberals -- tend to be clustered geographically in central city neighborhoods in big metropolitan areas. His big margins there helped him carry many electoral votes but not so many congressional districts.
And Obama's in-your-face liberalism, so apparent in last week's inaugural speech, antagonized some groups in a way that may hurt Democrats for some time to come.
The Obamacare contraception mandate helped Mitt Romney carry 59 percent of white Catholics -- probably their highest Republican percentage ever -- and 78 percent of white evangelical Protestants. These groups total 44 percent of the electorate.
That's a counterbalance to Obama's 93 percent among blacks and 71 percent among Hispanics. They were just 23 percent of the electorate, and while Hispanics will be a growing percentage, blacks probably won't.
It's going to be hard for other Democrats to replicate Obama's coalition in 2014 and 2016. It's not clear other Democrats can generate the turnout among blacks, Hispanics and young voters that he did.
And it's pretty clear that under the Obama aegis, Democrats can not make the kind of gains in congressional races that they did in 2006 and 2008.
Back then Democratic strategists Rahm Emanuel and Charles Schumer fielded moderate-sounding candidates in Republican-leaning territory who were able to win because of discontent with the performance of George W. Bush. When his job approval fell below 40 percent, Republican candidates almost everywhere were hurt.
Democrats in 2014 will have to run as members of the party led by Barack Obama. That could be a hard sell in the 24 states and 228 congressional districts that he failed to carry in November.
Take Georgia, where Republican Sen. Saxby Chambliss announced Friday he will not run for re-election next year. Obama got 45 percent of the vote there, his second-highest percentage in a state he didn't carry (the highest was in North Carolina).
Examination of the 2012 returns in Georgia's 159 counties and in its 14 congressional districts reveals unusually high turnout among black voters -- considerably higher than in the 2010 offyear or any election before 2008.
Georgia Democrats have high hopes of winning Chambliss's Senate seat. But it looks like an uphill climb.
George W. Bush's 51 percent re-election, with 11.5 million more votes than four years before, got his strategist Karl Rove musing about a permanent Republican majority. That didn't happen.
Now Barack Obama's 51 percent re-election, with 3.5 million fewer votes than four years before, has Democrats talking about annihilating the Republican Party. That's not likely to happen either.
Michael Barone, The Examiner's senior political analyst, can be contacted at email@example.com. His column appears Wednesday and Sunday, and his stories and blog posts appear on washingtonexaminer.com.