Republicans are about to deliver on the driving purpose of their House majority -- enacting Donald Trump's retribution.

Trump's lieutenants will on Thursday formally open an impeachment inquiry into Joe Biden that his supporters, smarting from their leader's own double impeachment, have been demanding since the current president took office.

The first hearing is taking place with just three days to reach a spending deal to keep the government open. Rather than try to solve the crisis, hardline House Republicans are driving the country toward a shutdown that Trump ordered up on social media, insisting it will will damage Biden, his potential general election rival.

The two showdowns -- and the return to power of Trump's movement in the House -- could shape the fate of the Republican House majority, which was narrowly won in last year's midterm elections.

The gravity of the House Oversight Committee embarking on an impeachment inquiry is being undermined by the GOP so far failing to show any evidence that the president corruptly benefited from his son Hunter's business dealings -- even if they presented a glaring conflict of interest.

House Republican leaders are initiating what should be a constitutional last-resort process that could oust a president at the same time that they are demonstrating their inability to fulfill their most basic duties, like passing bills and governing.

Extremist lawmakers are refusing to pass even a short-term funding bill to keep the government open and are seeking massive spending cuts on top of those agreed by Speaker Kevin McCarthy in a deal with Biden earlier this year -- to the chagrin of some Republicans in the Senate. Some of Trump's acolytes are seeking to end US aid to Ukraine in a move that would seriously undermine its battle for survival after an invasion ordered by Russian President Vladimir Putin, whom Trump has called a "genius." The Senate's bipartisan stopgap bill, which extends current funding levels for 45 days and includes $6 billion for Ukraine, stands no chance of passage in the House.

The discord on Capitol Hill is also bound up in the accelerating potential general election clash between Biden and Trump, which intensified this week when both rivals flew to Michigan to use an autoworkers strike in a bid to carve out an advantage in a critical swing state. Trump's speech on the issue on Wednesday night outside Detroit was also designed to overshadow the second Republican presidential debate in California, which he boycotted after reasoning that he is so far ahead in the polls that it wasn't worth his time.

Biden will follow up with a major speech on America's under-pressure democracy in Arizona on Thursday, which will take place against the backdrop of the impeachment hearing that Democrats see as a classic example of GOP abuses of power.

Two crisis springing from common causes

Impeachment and a shutdown brinkmanship are separate issues, but they spring from the same causes.

Both are bound up in the Republican House majority's devotion to Trump and his manipulation of the party to advance his ends. Trump thinks that Biden, rather than the GOP majority, will be blamed for a shutdown that will begin after midnight on Saturday, barring a long-shot deal between McCarthy and the rebels. And the impeachment drive, demanded by Trump acolytes almost since Biden's first day in office, seems at least partly to be retribution for Trump's impeachments and an attempt to distract from his four looming criminal trials by trying to damage Biden as his reelection bid heats up.

Each crisis is also symptomatic of the delicate balance of power that gave Republicans a narrow edge in the House. By depriving the GOP of a red wave last November, voters signaled that they were not fully comfortable with returning a party dominated by Trump's extremism to full authority on Capitol Hill. But paradoxically, the tiny House majority -- McCarthy can only lose four votes and still pass legislation on a party line -- has given the most extreme GOP members more leverage.

This has left McCarthy a weak speaker who cannot impose his writ on his party. He has, for instance, so far failed to push through even a short-term bill to keep the government open temporarily and twice was unable to pass a defense spending bill -- usually a routine duty members are keen to fulfill. Because of his tenuous power base, McCarthy has been forced to make a string of concessions to the far-right of his conference. Therefore, he is constantly at risk of facing a vote to oust him, a situation that curtailed his room for maneuver.

This is where impeachment comes in. The opening of the probe was widely seen as a concession to McCarthy's tormentors at the party's extremes and potentially an attempt to buy some leeway on the spending imbroglio that could cause a shutdown. If that was the plan, it failed miserably. Some House Republicans are now refusing to vote for any temporary spending extension expected to come over from the Senate. Others balk at passing a short-term extension at all -- reasoning it will lessen their chances of enacting a long-term package with massive spending cuts that would undermine the deal McCarthy did with Biden earlier in the year.

McCarthy will not be able to escape his moment of fate

It may not be now, but sooner or later, both the impeachment drama and the shutdown crunch will force McCarthy to adopt a high-risk strategy he is loath to take -- confronting the far right in a clash that will put the speakership, a position he has craved for years, on the line.

McCarthy may get off the hook if the impeachment inquiry does uncover direct evidence that Biden profited from his son's apparent conflict of interest and alleged influence peddling in Ukraine and China while his father was vice president. But given what little has been proven so far, a damning impeachment case seems a long way off. And it's hard to see McCarthy, in his vulnerable position, ending the impeachment probe on the basis that there is insufficient evidence.

On spending, McCarthy still appears to lack the votes to stave off a government shutdown. And he may need the spectacle and recriminations that could come from such an outcome -- and possible blame being heaped on his majority -- in order to build pressure on his conference to fall in line behind an eventual plan. As the 11th hour approaches, he's throwing a Hail Mary pass by seeking to include border security funding in a short-term spending fix to try to create divisions between his party's hardliners. "I don't understand somebody would want to stand with President Biden keeping an open border and not keep government open," the speaker said Wednesday. The Californian has also spoken in recent days about his experience of previous shutdowns that damaged Republicans. But his most rebellious members don't seem to be listening.

An impeachment that is seen as unjustified could also cause severe problems down the line for Republicans. Although the hardline wing is wielding significant influence on the conference, the road to the Republican majority in the 2022 midterm elections went through districts Biden carried in 2020 that Republicans flipped. If Republicans alienate those voters, they could lose their majority in November 2024. This is why there's been talk that some moderate Republicans could join Democrats in pushing a short-term funding rescue package of their own. And it explains why Rep. Mike Lawler of New York, one of the vulnerable GOP moderates, last week called his party a "clown show."

However, it's one thing to consider breaking with a speaker who is popular among many members -- it's another thing to leap. And any bipartisan plan to avert a shutdown would almost certainly prod insurgent Republicans to launch an immediate bid to rip the speaker's gavel from McCarthy's grasp.

Democrats are speaking as if a shutdown is already a fact, seeking to create a narrative that Republicans have ditched voters' priorities because of their desire to appease Trump and are unworthy of the responsibility of governing.

"We began the 118th Congress in chaos and we are still in chaos," Democratic Rep. Ayanna Pressley of Massachusetts told CNN's Jake Tapper on Wednesday. Biden, meanwhile, told reporters in San Francisco that he still hoped that a shutdown wouldn't happen. But he also set up a blame game by warning that vital work in science and health care, including cancer research, could be affected if federal agencies run out of funding. "So the American people need our Republican friends in the House of Representatives to do their job fund the government," he said.

The impact of a shuttered government would worsen as the days pass with no resolution. It could lead to significant hardships for those whose livelihoods depend on the government -- from troops going unpaid, and air traffic controllers, border patrol officers and Transportation Security Administration (TSA) workers at security checkpoints also working without wages. A prolonged impasse could damage an economy that has been resilient to a series of shocks coming out the pandemic but whose recovery is still not being felt by all Americans.

There is, however, one particular favorite function of government among Republicans that will sail on regardless. The House Administration Committee on Wednesday said that impeachments were "essential" so would not be disrupted.