(CNN) -- As Mitt Romney prepares to make the case for a first term, give a thought to what we can expect from a Barack Obama second term. 

It's probably going to look a lot like the second terms of George W. Bush, Bill Clinton, Ronald Reagan, and Richard Nixon -- driven not by his own agenda, but by events beyond his control. Bush's second term was defined by the after-effects of the Iraq decision he made in his first term; Clinton's by impeachment and the Internet boom; Reagan's by deficits and Gorbachev; Nixon's by Watergate. 

And what will define Obama's? 

1) Republicans will hold at least one House of Congress, maybe two. 

2) The U.S. economy will continue to mend, as the financial crisis recedes into the past. 

3) Unless forcibly prevented, Iran will enrich enough uranium for multiple nuclear weapons sometime before 2017. 

4) Natural gas production will continue to surge. 

Prediction 1 implies that there will be no bold Obama legislative agenda in a second term. The votes just won't be there. The second-term Obama agenda will have to be executed through agency action and executive order. And he'll have lots of opportunities via the big laws passed in his first term: the Affordable Care Act, Dodd-Frank, and so on. 

Critics often talk about how long these laws are. Yet however long the enactment, the text of a complex modern statute is only the very roughest guide to its future operation. The crucial operating decisions are made by presidential appointees, supervised by the courts. Congress drafts, but the administrators fill in the details - and the details, as the saying goes, are where the devil lurks. 
What is Mitt Romney doing?
Did George W. Bush have a second term?
Nixon?
Clinton?
Ford?
What was Bush's second term defined by?
Clinton's?
Reagan's?
Nixon's?
How many things does the article list that will define Obama's?
Will there be a bold Obama legislative agenda?
What will natural gas production do?
Will the votes be there?
What laws were passed in his first-term?
Are they lengthy laws?
Who are the operating decisions made by?
Who fills in the details?
preparing to make the case for a first term
As Mitt Romney prepares to make the case for a first term
yes
 the second terms of George W. Bush
yes
second terms of George W. Bush, Bill Clinton, Ronald Reagan, and Richard Nixon
yes
second terms of George W. Bush, Bill Clinton, Ronald Reagan, and Richard Nixon
unknown
unknown
his Iraq decision
Bush's second term was defined by the after-effects of the Iraq decision he made in his first term
impeachment and the Internet boom
 Clinton's by impeachment and the Internet boom
deficits and Gorbachev
Reagan's by deficits and Gorbachev
Watergate
 Nixon's by Watergate. 
Four
4)
no
Prediction 1 implies that there will be no bold Obama legislative agenda in a second term. 
continue to surge.
4) Natural gas production will continue to surge. 
no
 The votes just won't be there. 
the Affordable Care Act and Dodd-Frank
 the Affordable Care Act, Dodd-Frank, and so on. 
yes
Critics often talk about how long these laws are
presidential appointees
The crucial operating decisions are made by presidential appointees, 
administrators
 but the administrators fill in the details