The Trump administration is putting pressure on Senate Republicans to crack down on Democratic efforts to delay its agenda, fueling talk about the need for rules reform among Republicans on Capitol Hill.

Republicans are in discussions with Democrats about bipartisan changes to Senate rules to speed up consideration of President Trump's judicial and executive branch nominees, but if that effort flounders - as similar ones have in the past - they're not ruling out unilateral action.

White House patience with the Senate's backlog of nominees is wearing out, as Vice President Pence made clear during a private meeting with the Senate Republican Conference on Tuesday, according to lawmakers who attended the discussion.

White House legislative affairs director Marc Short on Friday accused Senate Minority Leader Charles Schumer (D-N.Y.) of "weaponizing" the rules to keep executive and judicial branch positions vacant.

Short noted that Democrats have required Republicans to hold 79 cloture votes on nominees during Trump's first 14 months in office.

"That's roughly five times the number of the last four administrations combined," he said.

A cloture vote ends dilatory action on a bill or nominee and is often used to end filibusters. It requires 60 votes to pass.

During the first 14 months of the past four administrations - a span of 56 months under Presidents Obama, George W. Bush, Clinton and George H.W. Bush - the Senate held 17 such votes, according to Short.

He promised that Trump would begin to speak out aggressively in response to what he called "historic obstruction."

"I think that perhaps I'm a warm-up act for him making a larger foray into this," Short told reporters.

He said Trump would "make his case to the American people that the objection has gotten ridiculous."

A spokesman for Schumer on Friday blamed the administration and Senate Republicans for the backlog of nominees.

"This administration has been historically slow in submitting nominations and has withdrawn more nominees in the first year than any of the past four administrations," said the Schumer aide.

The Democratic aide also noted there are currently 145 nominees awaiting action from Republican-controlled committees.

Trump has withdrawn more than 20 nominees and failed to submit nominations for State Department posts such as the ambassadorships for Cuba, Egypt, Honduras, Iceland, Ireland, Saudi Arabia, South Africa and Sweden.

Senate Republicans are reaching out to Democrats in hopes they might agree to changing the Senate rules to shorten the amount of time it takes to process nominees.

Sen. James Lankford (R-Okla.) is spearheading that effort.

"We're desperately behind on judges and noms," Lankford told The Hill. "We've had a cloture vote 80 times. That's more than the last four presidents combined."

A Republican aide said Lankford "has had some positive private conversations about this with Democrats, many of who realize that this trend is really, really bad."

But such bipartisan efforts have fallen short in the past, prompting speculation among some GOP senators that changing the rules with 51 votes - a controversial tactic known as the "nuclear option" - may be the only way to get something done.

"We need to reduce the amount of post-cloture time for nominees. The amount of time we now spend is ridiculous," said one GOP senator who requested anonymity to discuss Tuesday's conversation with Pence.

Senate rules require 30 hours to elapse on the floor once the Senate votes to end dilatory debate on a nominee, which empowers the minority party to eat up the calendar by refusing to yield back time.

The use of the nuclear option - which Senate Majority Leader Mitch McConnell (R-Ky.) employed last year to eliminate the Democrats' power to filibuster then-Supreme Court nominee Neil Gorsuch - wouldn't likely happen until the next Congress.

Republicans control only 51 seats and Sen. John McCain (R-Ariz.), who is undergoing treatment for brain cancer, hasn't voted since early December, reducing their effective majority to 50.

A single GOP defection would scuttle any attempt to change Senate precedent through a ruling of the chair, which needs to be sustained by a majority vote.

Republicans, however, hope to expand their majority. Sen. Cory Gardner (R-Colo.), chairman of the National Republican Senatorial Committee, pointed to an Axios poll this week showing that if the election were held today, Republicans could capture as many as five Democratic-held seats.

In a Wall Street Journal op-ed published in August, Lankford argued for shrinking the amount of time required to elapse after cloture has been filed on executive nominees from 30 hours to eight or less.

He pointed out that the Senate adopted this expedited process for a short time in 2013 under then-Senate Majority Leader Harry Reid (D-Nev.), who also invoked the nuclear option to eliminate filibusters for executive branch nominees and judicial nominees below the level of the Supreme Court.

"It worked then and it would work now," Lankford said.

There is strong support among junior Republican senators for changing the rules.

"The intention of the original filibuster and cloture was to allow for extended debate of issues, not for obstruction of a party's administration by delaying of nominee votes, so Sen. Perdue would like to see these rules changed," said Caroline Vanvick, a spokeswoman for Sen. David Perdue (R-Ga.).

Democrats argue that Republicans slow-walked Obama's nominees once they gained control of the Senate.

Senate Republicans forced cloture votes on 168 of Obama's nominees in 2015 and 2016, even though 62 of those nominees were later confirmed unanimously or by voice vote.

Democrats also argue that McConnell broke Senate tradition under Obama by holding up his nominee to the Supreme Court, Judge Merrick Garland, for 10 months, until Trump took office.

The action left the high court shorthanded for most of 2016.