US President Donald Trump has said he believes Barack Obama is behind a wave of protests against Republican lawmakers, and national security leaks.
He told Fox News: "I think President Obama's behind it because his people are certainly behind it", but added: "I also think it's just politics".
Mr Trump offered no evidence for his claims; his predecessor in the White House has not commented.
Mr Trump also spoke about his budget plans and other issues.
In his wide-ranging interview with Fox News' programme Fox and Friends, he said:
He gave himself a "C" on getting his message out but an "A" for achievement and "A+" for effort
He would be a "hypocrite" if he attended the White House Correspondents' Dinner, an annual event attended by journalists and politicians, in light of "fake news"
His plans to boost defence spending by $54bn (£43bn) would be paid for by a "revved up economy" - although analysts say boosting spending without adding to the deficit would be a challenge
President Trump's interview was broadcast hours before he is due to give his first address to a joint session of Congress in which he is expected to set out in greater detail his plans to cut spending and boost the economy.
A senior White House official told the BBC the president would talk about a "renewal of the American spirit", offering an "optimistic vision".
In the Fox News interview, he was asked about the protests faced by some Republican politicians at town hall meetings across the country.
He said he was certain Obama loyalists were behind both those protests and White House leaks. "In terms of him being behind things, that's politics. And it will probably continue," he added.
He was asked for more detail on how he would find the money for the 10% increase in military spending he has proposed for 2018. Proposed cuts elsewhere are unlikely to cover the proposed increase.
Mr Trump said he would get "more product for our buck" in terms of buying military hardware and would ask for a "form of reimbursement" from countries making use of the US military.
But he said his overall aim was to grow the economy.
"We were probably GDP of little more than 1% and if I can get that up to three or maybe more, we have a whole different ball game," he told the programme.
US government figures show that GDP in fact increased 1.6% in 2016, compared with 2.6% in 2015.
The White House sent Mr Trump's 2018 budget blueprint, which begins on 1 October, to federal agencies on Monday.
The agencies will then review the plan and propose changes to the cuts as the White House prepares for negotiations with Congress.
The Republican-controlled Congress must approve any federal spending.
Mr Trump's plan is expected to face backlash from Democrats and some Republicans over the planned cuts to domestic programmes.