The answer is for the same reason that they have so postured themselves that they have no options left under the Constitution to curb Obama's lawlessness because they conspicuously surrendered their constitutional power to control the purse and to impeach. Failing to exercise these constitutional prerogatives vested in the Congress to control a radical executive, Boehner and McConnell compounded the error by announcing that they would never shut down the government and never bring on impeachment.
The conventional explanation for national politicians stripping themselves of their own power is that they had fear of a backlash which they would argue Republicans experienced in the wake of the previous shutdown under Newt Gingrich and after the subsequent impeachment of Bill Clinton. But a close examination of those affairs reveals that the Republicans certainly were not substantially harmed in the election after the shutdown and the same argument to a lesser degree might be made concerning the impeachment of Bill Clinton. In any event, any criticism of the Republican impeachment of Bill Clinton must include criticism of the lack of unity and the ineptitude of the Republicans in making the case to the people.
The real reason that the Republican leaders in the House and the Senate have mounted no effective effort to curb Obama and indeed have noisily undermined any efforts to do so is quite selfish. First, they see no upside for themselves. But equally compelling to them, they succeeded in leaving the nation with no recourse in the face of the disintegration of the country and tyranny in Washington but to elect Republicans, meaning incumbent Republicans. In this course there is upside for them. They choose themselves over the country.
All else must give way to this selfish consideration. If it were otherwise we would hear these leaders throughout the Republican establishment in Congress and in the Republican National Committee preparing the nation for effective challenges to Obama. You would see them encouraging the kind of candidates, Tea Party candidates, who could be relied upon to utilize constitutional prerogatives to save the country. Instead, Karl Rove and the whole establishment empty their treasury to defeat Tea Party candidates.
They failed to tell us what they will do when they take office, we do not hear any plans anymore to repeal Obamacare. There is a cynical calculation that there will be enough disgruntled Americans to eke out the Republican majority in the Senate without upsetting anti-incumbent apple carts. The calculation is that conservatives will have no place else to go and dutifully troop to the polls to eke out majority the incumbents expect. To nationalize the election, to frame an over arching theory for reelection, is to upset the apple cart.
This policy of timidity is a calculated election tactic but it is being done in deference to big business contributors who want immigration amnesty and modified Obamacare. The establishment thinks it has chosen a middle way to keep the money pipeline open without offending the base.
Finally, people like Mitch McConnell harbor a rule or ruin ambition which says that to fill the Senate with the likes of Ted Cruz's to imperil his own position of leadership. The two approaches represented by Cruz and McConnell to governing ultimately cannot be reconciled because their view of liberty cannot be reconciled. More, one side, the grassroots side, sees the country descending into a dystopia and Karl Rove's side believes there is yet more blood to get out of this stone before the "deluge."
